US7929094B2 - Vertically-aligned liquid crystal display device having a rugged structure which is in contact with the liquid crystal layer - Google Patents

Vertically-aligned liquid crystal display device having a rugged structure which is in contact with the liquid crystal layer Download PDF

Info

Publication number
US7929094B2
US7929094B2 US11/109,936 US10993605A US7929094B2 US 7929094 B2 US7929094 B2 US 7929094B2 US 10993605 A US10993605 A US 10993605A US 7929094 B2 US7929094 B2 US 7929094B2
Authority
US
United States
Prior art keywords
liquid crystal
alignment
substrate
crystal layer
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
Application number
US11/109,936
Other languages
English (en)
Other versions
US20050237471A1 (en
Inventor
Tadashi Kawamura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sharp Corp
Original Assignee
Sharp Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sharp Corp filed Critical Sharp Corp
Assigned to SHARP KABUSHIKI KAISHA reassignment SHARP KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAWAMURA, TADASHI
Publication of US20050237471A1 publication Critical patent/US20050237471A1/en
Application granted granted Critical
Publication of US7929094B2 publication Critical patent/US7929094B2/en
Expired - Fee Related legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
    • E04H17/00—Fencing, e.g. fences, enclosures, corrals
    • E04H17/02—Wire fencing, e.g. made of wire mesh
    • E04H17/06—Parts for wire fences
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/13378—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
    • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
    • B29C59/046—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts for layered or coated substantially flat surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
    • E04H17/00—Fencing, e.g. fences, enclosures, corrals
    • E04H17/02—Wire fencing, e.g. made of wire mesh
    • E04H17/04—Wire fencing, e.g. made of wire mesh characterised by the use of specially adapted wire, e.g. barbed wire, wire mesh, toothed strip or the like; Coupling means therefor
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133753—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133753—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
    • G02F1/133757—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle with different alignment orientations
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133753—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
    • G02F1/133761—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle with different pretilt angles
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133776—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers having structures locally influencing the alignment, e.g. unevenness
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/13378—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation
    • G02F1/133792—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation by etching
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/1393—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/36—Micro- or nanomaterials

Definitions

  • the present invention relates to a liquid crystal display device and a method for producing the same.
  • LCD Liquid crystal display devices
  • TN Transmission Nematic
  • STN Super Twisted Nematic
  • a vertical alignment type LCD is an LCD which performs display in a normally black (NB) mode by employing a vertical alignment type liquid crystal layer provided between a pair of electrodes.
  • One method of achieving alignment control of a liquid crystal layer is a method which ensures that the liquid crystal layer has a pretilt with no voltage applied across the liquid crystal layer.
  • the alignment control of the liquid crystal has conventionally been realized by controlling the pretilt (or more specifically, a pretilt angle and a pretilt direction) of liquid crystal molecules by using a horizontal alignment film which have been subjected to a rubbing treatment.
  • the pretilt angle is determined by the material of the liquid crystal layer and the alignment films and the like, whereas the pretilt direction is determined by the rubbing direction.
  • liquid crystal molecules liquid crystal directors
  • pretilt angle a predetermined direction
  • pretilt direction a predetermined direction
  • the pretilt direction of the liquid crystal layer cannot be stably controlled even by performing a rubbing treatment for the vertical alignment films which are provided for the sake of alignment control.
  • a vertical alignment type liquid crystal display device has a higher contrast than that of the horizontal alignment type liquid crystal display device, even a slight non-uniformity in alignment can be visually recognized, thus resulting in display unevenness.
  • MVA mode Multi Domain Vertical Alignment
  • a plurality of regions (“domains”) having different orientation directions e.g., pretilt directions
  • a plurality of regions having different orientation directions (e.g., pretilt directions) are allowed to exist within each pixel, while ensuring that the areas of such domains are averaged out.
  • FIG. 1 As the simplest method for realizing alignment division, there has been disclosed a method which divides one pixel into four parts, as shown in FIG. 1 (e.g., Japanese Patent No. 2947350). Hereinafter, alignment division will be described by taking the method shown in FIG. 1 as an example.
  • liquid crystal molecules 12 located at a middle level along the direction of the liquid crystal layer in each of the four split regions (“domain”) are oriented in a direction substantially perpendicular to the face of each substrate 11 on which a vertical alignment film is formed.
  • a pair of polarizers 11 are disposed so that their transmission axes lie perpendicular to each other (cross Nicol) with the liquid crystal layer interposed therebetween, light is not transmitted through the liquid crystal layer, thus resulting in a “black” display state.
  • an aperture ratio is a ratio in area, to one pixel, of a portion of the pixel that allows light to be transmitted therethrough.
  • the structures of the substrates, electrodes, and like elements may become complicated, so that the productivity may be lowered and the production cost may increase with increase in the number of steps involved in the production process.
  • one method which is currently under study is, without using a rubbing treatment, forming vertical alignment films having a predetermined surface configuration, and controlling the pretilt direction of a vertical alignment type liquid crystal layer by utilizing the surface configuration of such vertical alignment films.
  • Proposals have been directed to a method which forms periodic undulations (ruggednesses) with a minute pitch on the surface of each vertical alignment film, and a method which provides a vertical alignment film on a base film having a predetermined surface configuration to control the surface configuration of each vertical alignment film.
  • a method has been proposed in which a vertical alignment film is applied to a substrate on whose surface an SiO film is formed by oblique evaporation (see, for example, T. UCHIDA, M. OHGAWARA, M. WADA, Jpn. J. Appl. Phys., 19, pp. 2127-2136 (1980)).
  • An SiO film which is obtained by oblique evaporation has a surface configuration characterized by an arrangement of minute columns (unit features).
  • the pretilt direction is controlled by the surface configuration of the SiO film.
  • UCHIDA et al. also describe that the pretilt angle can be controlled through adjustment of the surface configuration of the SiO film by varying the evaporation conditions.
  • the method proposed in UCHIDA et al. and the method proposed in Japanese Laid-Open Patent Publication No. 3-150530, supra, are both directed to producing a structure such as a substrate or a pressing die having a predetermined surface configuration, and forming a vertical alignment film having a surface configuration which reflects the surface configuration of that structure.
  • these methods have the following problems because oblique evaporation is utilized for producing such a structure.
  • KAWAI et al. lack any mention of causing a pretilt of vertically aligned liquid crystal molecules.
  • the ruggednesses which are described KAWAI et al. are obtained by allowing perpendicularly-intersecting sinusoidal interference fringes to exist, and therefore, there are limitations on the configuration and arrangement of the fine grooves that can be selected.
  • similar features are formed along two directions perpendicular to each other (x direction, y direction), it is difficult to separately control the features along the x direction from the features along the y direction. Therefore, when this method is applied to a display device of MVA mode, for example, the production process may be complicated.
  • the present invention has been made in order to overcome the problems described above, with a primary aim being to control liquid crystal alignment with a high precision by imparting a pretilt to a vertical alignment type liquid crystal layer, using a minute rugged structure (ruggedness) formed on a surface which is in contact with a liquid crystal layer.
  • a liquid crystal display device of the present invention is a liquid crystal display device comprising a pair of substrates, a vertical alignment type liquid crystal layer provided between the pair of substrates, and electrodes for applying a voltage to the vertical alignment type liquid crystal layer, wherein, at least one of the pair of substrates has a rugged structure on a surface which is in contact with the vertical alignment type liquid crystal layer; the surface having the rugged structure formed thereon has a region in which the height of the rugged structure varies along a first direction with a first period and varies along a second direction perpendicular to the first direction with a second period different from the first period; the first period is no less than 0.1 ⁇ m and no more than 10 ⁇ m, and the second period is no less than 0.1 ⁇ m and no more than 10 ⁇ m; and in the absence of an applied voltage, the vertical alignment type liquid crystal layer has a pretilt due to the rugged structure.
  • liquid crystal molecules located at a middle level along a thickness direction of the vertical alignment type liquid crystal layer are aligned so as to be tilted from a normal direction of the pair of substrates.
  • the first period is smaller than the second period.
  • the height of the rugged structure is equal to or greater than 0.2 times the first period. More preferably, the height of the rugged structure is equal to or greater than 0.5 times the first period.
  • the rugged structure comprises a plurality of unit features arranged in a two-dimensional array, each unit feature having an asymmetric cross section along the first direction.
  • Each unit feature may have a substantially triangular cross section along the first direction.
  • Each unit feature may have a substantially quadrangular cross section along the first direction.
  • Each unit feature may have a substantially trapezoidal cross section along the first direction.
  • One of base angles of the substantially trapezoidal cross section of each unit feature may be equal to or greater than 90° and less than 180°.
  • the unit features may be arranged with interspaces along the first direction.
  • the rugged structure may comprise a plurality of grooves arranged in the second direction.
  • Each groove may extend along the first direction.
  • Each groove may have a substantially quadrangular and symmetric cross section along the second direction.
  • each groove may have a width of no less than 0.1 ⁇ m and no more than 10 ⁇ m.
  • the rugged structure including rows A and rows B, each row A having the unit features arranged in the first direction and each row B being identical to the row A being shifted along the first direction by a distance which is less than an average period of the unit features; and the rows A and rows B alternate in the second direction.
  • Another liquid crystal display device of the present invention is a liquid crystal display device comprising a pair of substrates, a vertical alignment type liquid crystal layer provided between the pair of substrates, and electrodes for applying a voltage to the vertical alignment type liquid crystal layer, wherein, at least one of the pair of substrates has a rugged structure on a surface which is in contact with the vertical alignment type liquid crystal layer; the surface having the rugged structure formed thereon has a region in which the height of the rugged structure varies along a first direction with a first period and varies along a second direction perpendicular to the first direction with a second period which is equal to or different from the first period; the first period is no less than 0.1 ⁇ m and no more than 10 ⁇ m, and the second period is no less than 0.1 ⁇ m and no more than 10 ⁇ m; the rugged structure comprises a plurality of grooves each having a substantially quadrangular and symmetric cross section and extending in a direction different from the second direction; and in the absence of an applied voltage, the vertical alignment type liquid crystal layer has
  • a still another liquid crystal display device of the present invention is a liquid crystal display device comprising a pair of substrates, a vertical alignment type liquid crystal layer provided between the pair of substrates, and electrodes for applying a voltage to the vertical alignment type liquid crystal layer, wherein, at least one of the pair of substrates has a rugged structure on a surface which is in contact with the vertical alignment type liquid crystal layer;
  • the rugged structure includes rows A and rows B, each row A having a plurality of unit features arranged along a first direction with a first period, each row B being identical to the row A being shifted along the first direction by a distance which is less than an average period of the unit features, the rows A and rows B alternating in a second direction perpendicular to the first direction with a second period which is equal to or different from the first period;
  • the first period is no less than 0.1 ⁇ m and no more than 10 ⁇ m
  • the second period is no less than 0.1 ⁇ m and no more than 10 ⁇ m; and in the absence of an applied voltage, the
  • a still another liquid crystal display device of the present invention is a liquid crystal display device comprising a pair of substrates, a vertical alignment type liquid crystal layer provided between the pair of substrates, and electrodes for applying a voltage to the vertical alignment type liquid crystal layer, wherein, at least one of the pair of substrates has a rugged structure on a surface which is in contact with the vertical alignment type liquid crystal layer; the rugged structure comprises a plurality of unit features arranged along a first direction with a period of no less than 0.1 ⁇ m and no more than 10 ⁇ m, each unit feature having a substantially columnar shape; each bottom face surrounded by most adjacent ones of the plurality of unit feature lacks a symmetry axis of rotation in a substrate normal direction; and the vertical alignment type liquid crystal layer with no voltage applied thereacross has a pretilt due to the rugged structure.
  • liquid crystal molecules located at a middle level along a thickness direction of the vertical alignment type liquid crystal layer are aligned so as to be tilted from a normal direction of the pair of substrates.
  • the plurality of unit features have a height of no less than 0.1 ⁇ m and no more than 3 ⁇ m.
  • Each unit feature may be a triangular prism.
  • Each unit feature may be a pentagonal prism.
  • each unit feature has a shape which is determined in accordance with a specific location (position) of the unit feature on the substrate.
  • the rugged structure constitutes a plurality of subregions causing respectively different pretilt directions.
  • the rugged structure constituting the plurality of subregions may be provided on both of the pair of substrates, such that each subregion on one of the pair of substrates opposes a corresponding subregion on the other substrate in a one-to-one relationship.
  • the rugged structure constituting the plurality of subregions may be provided on both of the pair of substrates, such that each subregion on one of the pair of substrates opposes a corresponding plurality of subregions on the other substrate.
  • the rugged structure constituting the plurality of subregions may be provided on only one of the pair of substrates.
  • the liquid crystal display device further comprises a plurality of pixels arranged in a matrix, wherein, within a region corresponding to each pixel, the rugged structure constitutes a group of subregions causing respectively different pretilt directions.
  • the liquid crystal display device further comprises a plurality of pixels arranged in a matrix, wherein, within a region corresponding to each pixel, the rugged structure constitutes a plurality of groups of subregions causing respectively different pretilt directions, the groups of subregions being arranged with a pitch GP.
  • Each pixel may include a substantially rectangular aperture for allowing light to be transmitted therethrough, the aperture having a longer side extending along a column direction of the matrix of pixels and a shorter side extending along a row direction of the matrix of pixels; and the rugged structure may be split in stripes to constitute the plurality of subregions, each subregion extending in a direction which is parallel to neither the longer nor shorter side of the aperture.
  • a length H p of the longer side of each aperture may be substantially equal to an integer multiple of a length W p of the shorter side; the length W p of the shorter side may be substantially equal to an integer multiple of the pitch GP of the groups of subregions; and the subregions may extend in a direction at an angle of about 45° with respect to the shorter side of the aperture.
  • each subregion includes a plurality of minute regions causing respectively different pretilt angles.
  • the rugged structure has an embossed surface.
  • a method of producing the liquid crystal display device comprises the steps of: preparing a substrate having a rugged structure formed on a surface thereof; and providing a vertical alignment type liquid crystal layer between the substrate and another substrate opposing the substrate.
  • the step of preparing the substrate having the rugged structure formed on the surface thereof comprises the steps of: preparing a master having a surface configuration corresponding to the rugged structure; and embossing (or otherwise transferring) the surface configuration of the master onto the surface of the substrate.
  • the present invention by using a minute rugged structure which is formed on a surface which is in contact with a liquid crystal layer, a substantially uniform pretilt can be imparted to liquid crystal molecules which are located at a middle level along the thickness direction of the vertical alignment type liquid crystal layer.
  • the liquid crystal alignment can be controlled with a high precision, whereby high contrast display can be obtained.
  • the alignment of the liquid crystal layer can be regulated by a plane (two dimensions), the response characteristics can be improved.
  • alignment division can be realized by controlling the shape and/or arrangement of the rugged structure, the viewing angle characteristics can be improved.
  • FIG. 1 is a diagram for explaining alignment division.
  • FIGS. 2A and 2B are diagrams for explaining VAN mode.
  • FIGS. 3A and 3B are diagrams for explaining the concept of alignment control based on a rugged structure.
  • FIG. 4 is a diagram showing a simulation result of liquid crystal alignment.
  • FIG. 5 is a graph illustrating the relationship between unit feature shape and tilt angle as obtained from a simulation.
  • FIGS. 6A and 6B are diagrams for explaining alignment control for a parallel alignment type liquid crystal layer.
  • FIG. 7A is a diagram showing a simulation result of liquid crystal alignment in the case where no disclinations are introduced.
  • FIG. 7B is a diagram showing a simulation result of liquid crystal alignment in the case where disclinations are introduced.
  • FIGS. 8A and 8B are a perspective view and a cross-sectional view, respectively, showing an exemplary structure of an alignment controlling element.
  • FIGS. 8C and 8D are a perspective view and a cross-sectional view, respectively, showing another exemplary structure of an alignment controlling element.
  • FIGS. 9A and 9B are a plan view and a cross-sectional view, respectively, showing liquid crystal molecule orientations at the alignment controlling element surface shown in FIGS. 8C and 8D .
  • FIGS. 10A and 10B are schematic cross-sectional views illustrating exemplary structures of a liquid crystal display device of the present invention.
  • FIGS. 11A and 11B are schematic cross-sectional views illustrating exemplary structures of the liquid crystal display device of Embodiment 1.
  • FIGS. 12A and 12B are perspective views illustrating exemplary structures of an alignment controlling element according to Embodiment 1 of the present invention.
  • FIGS. 13A to 13C are diagrams for explaining parameters of an alignment controlling structure according to Embodiment 1 of the present invention.
  • FIGS. 14A and 14B are diagrams for explaining definitions of a tilt angle and a pretilt in the present invention.
  • FIGS. 15A and 15B are diagrams for explaining a patterning method which utilizes double beam interference exposure.
  • FIGS. 16A to 16D are perspective views each illustrating an exemplary structure of an alignment controlling element according to Embodiment 2 of the present invention.
  • FIGS. 17A and 17B are diagrams for explaining unit regions and subregion in an alignment controlling element.
  • FIGS. 18A and 18B are perspective views showing subregion constructions according to Embodiment 3 of the present invention.
  • FIGS. 19A to 19C are diagrams each illustrating an exemplary method of splitting a unit region into subregions.
  • FIGS. 20A and 20B are diagrams illustrating the outline of a replica technique according to Embodiment 4 of the present invention.
  • FIGS. 21A to 21D are cross-sectional views for explaining steps in a method of forming an alignment controlling element according to Embodiment 4 of the present invention.
  • FIG. 22 is a schematic illustration of an apparatus used in an emboss step according to Embodiment 4 of the present invention.
  • FIG. 23 is a schematic illustration of another apparatus used in an emboss step according to Embodiment 4 of the present invention.
  • FIG. 24 is a schematic illustration of yet another apparatus used in an emboss step according to Embodiment 4 of the present invention.
  • FIG. 25 is a schematic illustration of yet another apparatus used in an emboss step according to Embodiment 4 of the present invention.
  • FIGS. 26A to 26C are diagrams each illustrating an exemplary division pattern for a unit region.
  • FIGS. 27A and 27B are a plan view and a perspective view, respectively, showing pixel construction in an active matrix type liquid crystal display device.
  • FIG. 28 is a plan view illustrating exemplary pixel construction in a liquid crystal display device according to Embodiment 5 of the present invention.
  • FIG. 29 is a graph a showing light transmittance Tr when a voltage V is applied across a liquid crystal layer.
  • FIGS. 30A and 30B are perspective views each illustrating an exemplary subregion construction according to Embodiment 6 of the present invention.
  • FIG. 31A is a diagram illustrating an exemplary unit region construction according to Embodiment 6 of the present invention.
  • FIGS. 31B and 31C are charts illustrating results of transmittance measurement in the minute regions included in a unit region in FIG. 31A .
  • FIGS. 32A and 32B are a cross-sectional view and a plan view, respectively, showing the structure of an alignment controlling element according to Embodiment 7 of the present invention.
  • FIGS. 33A to 33E are diagrams for explaining a pitch, as well as angles of slanted faces or side faces, of unit features according to Embodiment 7 of the present invention.
  • FIGS. 34A to 34E are schematic cross-sectional views for explaining a method of producing an alignment controlling element according to Embodiment 7 of the present invention.
  • FIGS. 35A to 35E are schematic cross-sectional views for explaining another method for producing an alignment controlling element according to Embodiment 7 of the present invention.
  • FIGS. 36A to 36D are schematic cross-sectional views for explaining yet another method for producing an alignment controlling element according to Embodiment 7 of the present invention.
  • FIGS. 37A to 37C are diagrams for explaining the structure of an alignment controlling element according to Embodiment 8 of the present invention.
  • a minute rugged structure (or minute ruggednesses) is introduced to a surface which is in contact with a liquid crystal layer, the rugged structure placing the liquid crystal layer in a vertical alignment.
  • a rugged structure may be referred to as an “alignment controlling structure”.
  • Each unit feature 16 is composed of two faces (face A, face B) which are slanted in different directions, and has a substantially triangular cross-sectional shape.
  • a vertical alignment film is formed (not shown).
  • the vertical alignment film has a surface which reflects the surface configuration of the unit features 16 .
  • the liquid crystal molecules 17 in the liquid crystal layer are oriented so as to be perpendicular to the surface of the vertical alignment film.
  • any liquid crystal molecule located upon face B of the unit feature 16 is oriented as to be perpendicular to face B, whereas any liquid crystal molecule located upon face A is oriented so as to be perpendicular to face A.
  • the unit features 16 have a period (pitch) P which is about the same as the pixel pitch (e.g., 100 ⁇ m)
  • P the pixel pitch
  • the liquid crystal molecules 17 would be oriented in the normal direction of face B, and thus tilted with respect to the normal of the substrate 15 .
  • the repetition period P of unit features 16 is made shorter than the pixel pitch, a plurality of unit features 16 will be formed within one pixel.
  • different orientations i.e., an orientation ascribable to face A and an orientation ascribable to face B, will be present.
  • the aperture ratio will be decreased in that case, thus resulting in a dark display and making it necessary to adjust the area ratio between face A and face B.
  • the alignment controlling element 15 will act as a diffraction grating with respect to visible light, thus causing coloration of the pixels when applied to a liquid crystal display device. Therefore, in order to realize satisfactory display, it is desirable that the period P is no less than 1 ⁇ m.
  • FIG. 4 shows the result of this simulation.
  • the liquid crystal layer used in the simulation had a thickness of 20 ⁇ m.
  • the orientations of liquid crystal molecules 17 s located at an interface between the liquid crystal layer and each unit feature 16 are determined by slanted faces A and B of the unit feature 16 .
  • the liquid crystal molecules which are distant from the unit features 16 are unlikely to be influenced by the slanted faces, so that liquid crystal molecules 17 c located at a middle level along the thickness direction of the liquid crystal layer (hereinafter referred to as “central molecules”) are hardly tilted with respect to the normal direction of the substrate 15 .
  • FIG. 5 The horizontal axis of the graph of FIG. 5 represents a ratio A/P of the width of face A to the repetition period P of the unit features 16 , whereas the vertical axis represents the angle (tilt angle) between the longer axes of the central molecules and the substrate surface in the absence of an applied voltage. From the results shown in FIG. 5 , it can be seen that a similar trend to the simulation result shown in FIG. 4 exists even though the area ratio between face A and face B and the height H of each unit feature 16 is varied. The central molecules are hardly tilted with respect to the substrate normal direction.
  • the simulation results shown in FIG. 4 and FIG. 5 would indicate that the unit features 16 cannot impart a sufficient pretilt (e.g., a tilt angle of about 87° or about 93°; that is, an angle of about 3° between the liquid crystal molecules and the substrate normal) for the liquid crystal molecules located at a middle level along the thickness direction of the liquid crystal layer.
  • a sufficient pretilt e.g., a tilt angle of about 87° or about 93°; that is, an angle of about 3° between the liquid crystal molecules and the substrate normal
  • the liquid crystal alignment as determined at the interface between the liquid crystal layer and the substrate (alignment film) will be retained across the thickness direction of the liquid crystal layer.
  • the liquid crystal molecules will be oriented in accordance with the ruggednesses, as long as the ruggednesses consists of a fine pattern (e.g., 10 ⁇ m or less).
  • the liquid crystal molecules will be reoriented so as to minimize strain in terms of orientation distribution.
  • any local change (tilting direction and tilting angle) which has been imparted by the ruggednesses to the liquid crystal molecule 17 s will be gradually averaged out along the thickness direction of the liquid crystal layer.
  • the unit features 16 will not enable undulation-based alignment control to be applied to a liquid crystal display device.
  • the average period P of the unit features must be kept no less than 10 ⁇ m, and the shape and size of the unit features 16 will also need to be optimized so that the liquid crystal alignment can be controlled across the thickness direction of the liquid crystal layer.
  • FIGS. 7A and 7B illustrate examples where alignment control for a liquid crystal layer is performed by using a substrate 30 on whose surface unit features 31 are arranged, each unit feature 31 having a cross section in the form of a parallelogram.
  • FIG. 7A is a diagram showing the liquid crystal alignment in the case where no disclinations exist.
  • the orientations of the liquid crystal molecules 32 c and 32 d are respectively restricted by face C and face D composing the unit feature 31 .
  • the liquid crystal molecules 32 c located upon face C and the liquid crystal molecules 32 d located upon face D are tilted in respectively different directions.
  • these tilting directions become more averaged out as the liquid crystal molecules are located farther away from the unit feature 31 , such that liquid crystal molecules 33 which are located at a middle level along the thickness direction of the liquid crystal layer are oriented substantially perpendicular to the substrate 30 .
  • disclinations can be intentionally caused by optimizing the shape and/or arrangement of the unit features 31 .
  • the orientation of the liquid crystal molecules as restricted by the slanted side face (face C) of the unit feature 31 and the orientation of the liquid crystal molecules as restricted by the substrate surface (bottom face) cannot maintain continuity in the thickness direction of the liquid crystal layer, thus causing disclinations in a region sandwiched between face C and the substrate surface. Since the orientational continuity is broken due to the disclinations, the orientation force from face C is not transmitted to any liquid crystal molecules distant from face C.
  • the influence which face C exerts on the orientation of the liquid crystal molecules in the entire liquid crystal layer is reduced, whereas the orientation force of face D becomes dominant.
  • the liquid crystal molecule orientation as restricted by the side face (face C) may be said to be “confined within a space”.
  • the disclinations as shown in FIG. 7B are utilized to substantially uniformly control the alignment of the liquid crystal molecules 33 which are located at a middle level along the thickness direction of the liquid crystal layer.
  • the aforementioned ruggednesses may be provided on any surface which is in contact with a liquid crystal layer, e.g., a TFT substrate, or a color filter substrate of a liquid crystal display device.
  • a liquid crystal layer e.g., a TFT substrate, or a color filter substrate of a liquid crystal display device.
  • any substrate including a TFT substrate, a color filter substrate, a glass substrate or the like
  • an alignment controlling element any substrate (including a TFT substrate, a color filter substrate, a glass substrate or the like) on whose surface an alignment controlling structure is provided will be collectively referred to as an “alignment controlling element”.
  • FIG. 8A is a perspective view of an alignment controlling element 20 including unit features 31 each having a quadrangular cross section.
  • FIG. 8B is an E-E′ cross-sectional view of the alignment controlling element 20 .
  • each unit feature 31 On the surface of the alignment controlling element 20 , the unit features 31 are arranged in a two-dimensional array. Each unit feature 31 has a cross section which is asymmetric along an X direction.
  • the alignment controlling element 20 has a plurality of grooves 35 formed therein. Each groove 35 extends in a direction which is not perpendicular to the X direction, and may extend, for example, along the X direction.
  • the alignment controlling element 20 it is possible to cause disclinations in the hatched areas shown in FIG. 8B , i.e., each region 21 surrounded by side walls of adjoining unit features and the substrate surface.
  • disclinations in the hatched areas shown in FIG. 8B i.e., each region 21 surrounded by side walls of adjoining unit features and the substrate surface.
  • the specific size and pitch of the unit features will be discussed later.
  • the unit features may have any asymmetric cross-sectional shape, e.g., a triangle.
  • the grooves 35 in the alignment controlling element 20 are provided in order to prevent the liquid crystal molecules from rotating in an azimuth angle direction under a high applied voltage, as described below.
  • the liquid crystal molecules are vertically aligned in the absence of an applied voltage ( FIG. 2A ).
  • the liquid crystal molecules become aligned in parallel to the substrate ( FIG. 2B ). If the grooves 35 were not formed in the alignment controlling element 20 , when the liquid crystal molecules near the surface of the alignment controlling element 20 take a near-parallel posture to the substrate upon the application of a voltage, the liquid crystal molecules would try to align in the direction of the gaps between unit features, based on a principle similar to that described in FIGS. 6A and 6B with respect to the liquid crystal molecules 17 .
  • the gaps between unit features extend in a direction perpendicular to the orientation direction of the liquid crystal molecules in the absence of an applied voltage.
  • the motion of the liquid crystal molecules would switch from a motion in a polar angle direction to a motion in an azimuth angle direction. This makes it difficult to increase the voltage to be applied in a white display state, thus hindering satisfactory display.
  • the liquid crystal molecules will try to align along the grooves 35 upon the application of a voltage, thus being prevented from rotating in an azimuth angle direction.
  • Each unit feature 31 is asymmetric with respect to a plane which is perpendicular to the X direction and to the substrate surface. Therefore, the surface of the alignment controlling element 20 is asymmetric with respect to azimuthal direction. In other words, the height of the surface of the alignment controlling element 20 periodically changes both along the X direction and along a Y direction which is perpendicular to the X direction, such that the period of height change along the X direction is different from the period of height change along the Y direction.
  • the alignment controlling element 20 by disposing the alignment controlling element 20 so that its surface is in contact with the liquid crystal layer, not only is it possible to impart a pretilt to the liquid crystal layer in the absence of an applied voltage based on the cross-sectional shape (which is asymmetric along the X direction) of each unit feature 31 , but it is also possible to restrict the liquid crystal molecule orientations under a high applied voltage, based on changes in the surface height along the Y direction (as exemplified by the periodic grooves 35 ).
  • the ruggednesses of the alignment controlling element 20 are optimized in terms not only of the cross-sectional shape but also of the shape along the depth direction. Therefore, the liquid crystal alignment can be controlled in both a black display state and a white display state. As a result, high quality display can be obtained.
  • disclinations are caused by breaking continuity in the thickness direction of the liquid crystal layer, by taking advantage of the orientation force from slanted face C of the unit features 31 and the orientation force from the substrate surface as has been described with reference to FIGS. 7A and 7B .
  • disclinations may be caused by breaking orientational continuity within the plane of the liquid crystal layer.
  • an alignment controlling element 40 shown in FIGS. 8C and 8D acts so that the orientations of liquid crystal molecules 17 w as restricted by the side faces of unit features 41 which extend substantially perpendicularly with respect to the substrate surface and the orientation of liquid crystal molecules 17 g as restricted by the substrate surface (bottom face) cannot maintain continuity within the plane of the liquid crystal layer, thus causing disclinations along the side faces of each unit feature 41 . Due to such disclinations, the orientations of the liquid crystal molecules as restricted by the side faces of the unit features 41 are “confined within a planar region” which is defined by the bottom face 42 and substantially surrounded by the side faces of each unit feature 41 .
  • FIG. 8C is a perspective view showing another exemplary structure of the alignment controlling element of the present invention.
  • the alignment controlling element 40 shown in FIG. 8C includes a plurality of triangular-prism-like unit features 41 .
  • the upper face of each unit feature 41 may be an isosceles triangle, for example.
  • FIG. 8D is a plan view of the alignment controlling element 40 .
  • each gap (dent) between adjoining unit features 41 has a bottom face 42 in the shape of an isosceles triangle.
  • liquid crystal When liquid crystal is aligned with the alignment controlling element 40 , it is possible to confine liquid crystal alignment within a planar region defined by the bottom face 42 . This principle will be described below, with reference to FIGS. 9A and 9B .
  • FIGS. 9A and 9B are a plan view and a Z-Z′ cross-sectional view, respectively, showing the orientations of interfacial liquid crystal molecules at an interface between the alignment controlling element 40 and the liquid crystal layer.
  • liquid crystal molecules 17 p near the upper face of each unit feature 41 are aligned so as to be perpendicular to the upper face of the unit feature 41 .
  • liquid crystal molecules 17 b are compelled to align in a direction parallel to the bottom face 42 and substantially perpendicular to the bottom side of the isosceles triangle defining the bottom face 42 .
  • liquid crystal molecules 17 g in the gap of each unit feature 41 are aligned substantially similarly to the liquid crystal molecules 17 b due to the influence of the liquid crystal molecules 17 b at the bottom face 42 , except that the liquid crystal molecules 17 w located near either side wall of each unit feature 41 are aligned so as to be perpendicular to that side wall of the unit feature 41 .
  • the orientation of the liquid crystal molecules 17 b at the bottom faces 42 and the orientation of the liquid crystal molecules 17 p at the upper faces of the unit features 41 .
  • the liquid crystal molecules in the overall liquid crystal layer are aligned in a direction which averagely combines these two orientations, thus resulting in a vertically alignment which is tilted in a specific direction.
  • alignment control within this liquid crystal layer can be realized by controlling the above two orientations that are imparted to the interfacial liquid crystal molecules, while ignoring any other orientations (e.g., those of the liquid crystal molecules 17 w near the side walls of the unit features 41 ).
  • the shape of the upper face and the shape of the bottom face 42 of each unit feature 41 are not limited to the shapes shown in FIGS. 8C and 8D .
  • the bottom face 42 has a shape which has a symmetry axis of rotation in the substrate normal direction (e.g., a regular triangle, a square, or a rectangle)
  • a symmetry axis of rotation in the substrate normal direction e.g., a regular triangle, a square, or a rectangle
  • a structure for causing disclinations within a planar region (such as the alignment controlling element 40 shown in FIGS. 8C and 8D ) can be produced more easily than a structure for causing spatial disclinations (such as the alignment controlling element 20 shown in FIGS. 8A and 8B ).
  • the surface of the alignment controlling element needs to have ruggednesses which vary along the thickness direction of the liquid crystal layer (as exemplified by the unit features 31 of the alignment controlling element 20 ).
  • the ruggednesses may be formed so as to be always vertical with respect to the substrate (as exemplified by the triangular-prism-like unit features 41 ), and therefore can be produced with an exposure apparatus which is usually employed for display device production, e.g., a stepper.
  • a liquid crystal display device having a structure as shown in FIG. 10A or 10 B can be obtained, for example.
  • an alignment controlling element 483 which has a conductive film 485 and a vertical alignment film 487 formed in this order on its surface, opposes a substrate 480 which has an electrode 481 and a vertical alignment film 488 formed on its surface.
  • a liquid crystal layer 490 is interposed between the alignment controlling element 483 and the substrate 480 .
  • the vertical alignment film 487 is formed so as to be in contact with the liquid crystal layer 490 .
  • the liquid crystal layer 490 is a vertical alignment type liquid crystal layer.
  • the alignment controlling element 483 has an undulated surface as described with reference to FIGS. 8A to 8D , the ruggednesses acting to cause alignment of the liquid crystal molecules in the liquid crystal layer 490 .
  • the liquid crystal molecules (central molecules) contained in the liquid crystal layer 490 are influenced by the surface configuration of the alignment controlling element 483 , so as to be tilted from the normal direction of the substrate.
  • the liquid crystal molecules When a voltage is applied across the liquid crystal layer 490 by means of the conductive film 485 and the electrode 481 , the liquid crystal molecules further incline in the direction in which they were tilted in the OFF state.
  • another alignment controlling element may be employed so as to oppose the alignment controlling element 483 , such that the liquid crystal layer 490 is interposed between the two alignment controlling elements.
  • a display device 701 shown in FIG. 10B has a similar structure to that of the display device 700 shown in FIG. 10A . However, in the display device 701 , a conductive film 482 is formed between a substrate and an alignment controlling element 484 .
  • the unit features of the alignment controlling element 483 may be formed of an organic substance such as acrylic resin or rubber, e.g., photoresist, UV-curable resin, thermosetting resin, or epoxy resin, or an inorganic substance such as a metal (e.g., Al, Ta, or Cu), a semiconductor (e.g., Si or ITO), or an insulative material (e.g., SiO 2 or SiN). It is preferable that the unit features are formed of a material having such characteristics as to cause liquid crystal to be vertically aligned (e.g., fluoroplastic) because then it is no longer necessary to apply the vertical alignment film 488 to the surface of the alignment controlling element 483 , whereby the production process can be simplified.
  • an organic substance such as acrylic resin or rubber, e.g., photoresist, UV-curable resin, thermosetting resin, or epoxy resin
  • an inorganic substance such as a metal (e.g., Al, Ta, or Cu), a semiconductor (e.g., Si or
  • the orientations of the central molecules in the liquid crystal layer 490 can be substantially uniformly controlled due to the ruggednesses provided on the surface of the alignment controlling element 483 , so that high contrast display can be obtained.
  • any arbitrary liquid crystal alignment i.e., tilting direction and tilting angle of the liquid crystal molecule from the substrate normal
  • an improved retardation and aperture ratio can be obtained.
  • the display devices 700 and 701 are MVA mode liquid crystal display devices.
  • alignment division can be freely and easily realized by controlling the ruggednesses of the alignment controlling element 483 with respect to specific locations (coordinates) on the substrate the ruggednesses formed thereon. That is, the ruggednesses are changed to define domains of the MVA mode liquid crystal display devices. Since no such complicated alignment controlling means (e.g., ribs or slits) as in the conventional cases need to be formed, the production process can be simplified.
  • the display devices 700 and 701 also have an advantage in that better response characteristics can be realized than by display devices which utilize ribs or slits. This advantage will be described below.
  • Alignment controlling means such as ribs or slits, which are employed in conventional MVA mode liquid crystal display devices, are only locally (in a one dimensional array) deployed in the liquid crystal layer, with respect to each pixel. Therefore, within each pixel which actually has a two-dimensional expanse, the liquid crystal molecules near the alignment controlling means may respond relatively rapidly, whereas any liquid crystal molecules in positions unlikely to receive the influence of the alignment controlling means may become slow in response. Such response characteristics distribution may lead to poorer display characteristics.
  • liquid crystal molecules present in the neighborhood of the ribs will have a predetermined pretilt (pretilt direction and pretilt angle) due to the influence of the rib shapes.
  • pretilt direction and pretilt angle any liquid crystal molecule located in the middle of adjoining ribs is unlikely to be influenced by the rib shapes, so that the pretilt angle of such liquid crystal molecules becomes smaller than that of the liquid crystal molecules in the neighborhood of the ribs.
  • the liquid crystal molecules will incline in the pretilt direction only one after another, those with greater pretilt angles first, thus reducing the response speed of the liquid crystal layer.
  • the liquid crystal molecules present in the neighborhood of the slits will receive greater influence of fringe field s than do the liquid crystal molecules which are present in the middle of slits.
  • the liquid crystal molecules will respond only one after another, those closer to the slits first, thus resulting in a prolonged response time of the liquid crystal layer.
  • a planer (two-dimensional) alignment controlling means of the liquid crystal layer 490 can be formed uniformly over substantially the entire pixel region, so that the liquid crystal molecules will respond quickly, irrespective of the specific position in the liquid crystal layer 490 .
  • the response speed of the liquid crystal layer 490 can be greatly improved from the conventional level.
  • undulation-based liquid crystal alignment control is performed also in a ZBD (Zenithal Bistable Device) which operates in a bistable liquid crystal mode. Alignment control in ZBDs is described in Japanese National Stage Publication Nos. 2002-500383 and 2003-515788, for example.
  • ZBD Zero-Step Bipolar Bipolar Device
  • the orientation state (pretilt angle, pretilt direction) as determined by the ruggednesses of the alignment controlling element does not change in response to the application of voltages of different polarities (e.g., within a range from ⁇ 5V to +5V); in other words, bistability is not exhibited.
  • a bistable liquid crystal mode liquid crystal display device is generally plagued by transmittance hysteresis which occurs in response to voltage application, whereas the liquid crystal display device of the present invention is free of such transmittance hysteresis, so that excellent gray scale display can be realized.
  • FIGS. 11A and 11B are schematic cross-sectional views illustrating exemplary structures of the liquid crystal display device of the present embodiment.
  • the liquid crystal display device shown in FIG. 11A includes a pair of alignment controlling elements 50 attached together via spacers (thickness: 5 ⁇ m) 65 , and a liquid crystal layer 66 interposed therebetween.
  • the alignment controlling element 50 includes a glass substrate 61 and an electrode 62 formed on the glass substrate 61 , with an alignment controlling structure being formed on the electrode 62 .
  • the alignment controlling structure includes an arrangement of a plurality of unit features 51 .
  • the unit features 51 are formed of, for example, a resin material. Each unit feature 51 has an asymmetric quadrangular cross section.
  • grooves (not shown) are formed in a direction perpendicular to the direction in which the unit features 51 are arranged.
  • a vertical alignment film 64 is formed on the surface of the unit features 51 .
  • the vertical alignment film 64 is in contact with the liquid crystal layer 66 .
  • the liquid crystal display device shown in FIG. 11B includes an alignment controlling element 50 , a counter substrate 61 ′, and a liquid crystal layer 66 interposed therebetween.
  • the alignment controlling element 50 has a similar structure to that of the alignment controlling element 50 of the sample device shown in FIG. 11A .
  • the counter substrate 61 ′ includes an electrode 62 and a vertical alignment film 64 formed on the surface of the electrode 62 .
  • the surface of the vertical alignment film 64 provided on the counter substrate 61 ′ is flat.
  • the pretilt angle of the central molecules i.e., the liquid crystal molecules located at a middle level along the thickness direction of the liquid crystal layer 66
  • the pretilt angle of the central molecules in the liquid crystal display device shown in FIG. 11B will be about 1 ⁇ 2 of the pretilt angle of the central molecules in the liquid crystal display device shown in FIG. 11A .
  • the alignment controlling element 50 used in the liquid crystal display device of the present embodiment includes unit features 51 having a quadrangular cross section, the cross-sectional shape of the unit features 51 may be a triangle or any other shape, as long as it is asymmetric.
  • FIG. 12A is a perspective view illustrating another exemplary structure of the alignment controlling element of the present embodiment.
  • the alignment controlling element 70 shown in FIG. 12A includes a plurality of rows 71 c of unit features.
  • Each row 71 c of unit features includes a plurality of unit features 71 which are arranged along the X direction with a pitch P.
  • Each unit feature 71 has a substantially triangular cross section.
  • the rows 71 c of unit features are arranged along the Y direction at predetermined intervals (grooves 72 ), with a pitch PG.
  • the grooves 72 extend along the X direction.
  • the length of each groove 72 along the Y direction is defined as a width G.
  • the liquid crystal molecules will try to align along the grooves 72 under a high applied voltage, whereby the liquid crystal molecules are prevented from rotating in an azimuth angle direction.
  • the grooves 72 have a cross-sectional shape which is symmetric along the Y direction (e.g., a rectangle).
  • the rotation of liquid crystal molecules under a high applied voltage can be prevented without affecting the pretilt, which is determined by the cross-sectional shape of each unit feature 71 , which is asymmetric along the X direction.
  • the alignment controlling element 70 of the present embodiment is not limited to the structure shown in FIG. 12A , but any structure may be adopted as long as not only the cross-sectional shape of each unit feature but also the shape of each unit feature along the depth direction are controlled so that the liquid crystal molecules are prevented from rotating in an azimuth angle direction under a high applied voltage.
  • a structure as shown in FIG. 12B may be adopted, in which rows 73 c of unit features and rows 73 c ′ of unit features alternate along the Y direction, where each row 73 c ′ of unit features is identical to each row 73 c of unit features being translated along the X direction by 1 ⁇ 2 of the pitch P along the X direction.
  • the height of the surface of the alignment controlling element 70 changes along the X direction with the pitch P, and changes along the Y direction with the pitch PG.
  • the height change along the X direction differs from the height change along the Y direction.
  • the pitch P along the X direction and the pitch PG along the Y direction can each be arbitrarily selected, and the pitches P and PG may or may not be equal. The aforementioned effect of preventing the rotation of liquid crystal molecules under a high applied voltage can be obtained even if the pitch PG along the Y direction is not so small as the pitch P along the X direction.
  • the pretilt direction and pretilt angle which are imparted to a liquid crystal layer are basically determined based on the cross-sectional shape of each unit feature 71 or 73 along the X direction. Therefore, even if the shape along the depth direction of the unit features 71 or 73 is only changed while conserving their cross-sectional shape, no substantial change in the pretilt will occur.
  • various parameters defining the cross-sectional shape of the unit features are studied. Note that the results of the study will basically be unaffected by the pitch or shape of the grooves 72 , or the presence or absence of the grooves 72 .
  • an alignment controlling element having the structure as shown in FIG.
  • the actual pretilt angle which is imparted to the liquid crystal layer tends to be smaller than the pretilt angle as determined by the cross-sectional shape of the unit features 71 or 72 . In this case, it would therefore be necessary to adjust the cross-sectional shape of the unit features 71 or 73 to obtain a desired pretilt angle.
  • Any alignment controlling element of the present embodiment can be produced by using an electron beam lithography apparatus, for example.
  • a method for producing the alignment controlling element 70 will be described as one example.
  • a photoresist layer (thickness: e.g., 1 ⁇ m) is formed on the surface of a substrate by spin-coating.
  • a glass substrate having a conductive film formed on its surface is used as the substrate, with THMR-IP3300 being used as a photoresist.
  • the photoresist layer is processed into a fine pattern.
  • unit features 71 arranged as shown in FIG. 12A are to be formed. More specifically, by using an electron beam lithography apparatus, an exposure and then a development for the photoresist layer are performed.
  • the slanted faces (side walls) of the unit features 71 can be formed by varying the beam intensity of the exposure apparatus at the time of exposure.
  • the alignment controlling element 70 is obtained.
  • the method for producing the alignment controlling element of the present embodiment is not limited to the above.
  • a hologram technique or a double beam interference exposure technique may be used.
  • grooves 72 may be formed in a direction perpendicular to the stripes, with the pitch PG.
  • the grooves 72 can be formed by etching or laser ablation.
  • the liquid crystal display device of the present embodiment can be produced by using the alignment controlling element 70 which has been produced by the above-described method, for example. Specifically, in the case of producing a liquid crystal display device having the structure as shown in FIG. 11A , two alignment controlling elements 70 are formed, and attached together via spacers having a thickness of 5 ⁇ m. Thereafter, a liquid crystal material having a negative ⁇ is injected between the alignment controlling elements 70 . As the liquid crystal material, MLC6609 (from MERCK&CO., Inc.) is used. In the case of producing a liquid crystal display device having the structure as shown in FIG. 11B , a similar method may be employed except that a counter substrate 61 ′ having an electrode 62 and a vertical alignment film 64 formed thereon is used instead of one of the alignment controlling elements 50 .
  • alignment control for the liquid crystal layer is realized by the ruggednesses on the surface of the alignment controlling element. At this time, in order to substantially uniformly control the orientation of the central molecules in the liquid crystal layer, it is necessary to cause disclinations in a region (space) near the surface of the alignment controlling element, as shown in FIG. 7B .
  • the inventors have specifically investigated into the possible surface configurations (alignment controlling structures) of the alignment controlling element for causing disclinations. The results are discussed below.
  • FIGS. 13A and 13B are a perspective view and a cross-sectional view, respectively, of the alignment controlling element 50 .
  • a plurality of unit features 51 are arranged on the surface of the alignment controlling element 50 .
  • the cross-sectional shape of each unit feature 51 is substantially trapezoidal.
  • the pitch of the unit features 51 is denoted as “P”
  • the height of each unit feature 51 is denoted as “H”
  • the width of the upper face of each unit feature 51 is denoted as “W”
  • the angles (base angles) between the substrate surface and the respective side walls of each unit feature 51 are denoted as “A” and “B”
  • the width of a gap between adjoining unit features 51 is denoted as “F”.
  • the pitch P of the unit features 51 is no less than 1 ⁇ m and no more than 10 ⁇ m, as described before.
  • the values of these parameters P, H, W, A, B, and F should be appropriately chosen in accordance with the specific pretilt to be imparted to the liquid crystal layer.
  • the angle A between one of the side walls of the cross-sectional shape of each unit feature and the substrate surface may be 90° or more; in this case, the above parameters are as defined in FIG. 13C .
  • the cross-sectional shape of each unit feature may alternatively be a triangle; in this case, the width W of the upper face is zero.
  • a “pretilt direction” is defined as the tilting direction of the liquid crystal molecules (liquid crystal directors) in the absence of an applied voltage to the liquid crystal layer, as projected onto the plane of the substrate surface.
  • the angle between the tilting direction of the liquid crystal molecules and the substrate surface is defined as a “tilt angle ⁇ ”.
  • the angle between the tilting direction of the liquid crystal molecules and the substrate surface is defined as a “pretilt angle Ph”.
  • the inventors produced a sample device having the structure as shown in FIG. 11A .
  • the method of production will be described below.
  • alignment controlling elements 50 to be used for the sample device are produced.
  • a photoresist layer (thickness: 1 ⁇ m) is formed by spin-coating, for example.
  • THMR-IP3300 is used as a photoresist.
  • a glass substrate 61 having an electrically conductive layer (ITO) 62 formed on its surface is used as a transparent substrate.
  • the photoresist layer is patterned by using double beam interference exposure.
  • the substrate 61 is placed on a prism (prism angle: ⁇ ) 69 , which is provided on an Al mirror 68 .
  • the substrate 61 is exposed to Kr laser light 67 having a wavelength of 407 nm.
  • FIG. 15B light which is incident to the substrate at an incident angle i is led through the substrate so as to be refracted within the prism, then reflected from the Al mirror, and thereafter goes out again from the substrate surface at an outgoing angle of ⁇ .
  • the photoresist layer can be subjected to a desired intensity distribution.
  • unit features 51 having a height of 1 ⁇ m or less and having an asymmetric quadrangular cross section are formed on the surface of the substrate 61 .
  • This patterning method is advantageous in that the pitch and the angles of the slanted faces, etc., of the unit features 51 can be freely set based on the incident angle i, prism angle ⁇ , the refractive index of the prism, and the like.
  • a vertical alignment film 64 is applied onto the surface of the substrate 61 on which the unit features 51 have been formed.
  • an alignment controlling element 50 is obtained.
  • Two alignment controlling elements 50 are formed by using the above-described method, and the resultant alignment controlling elements 50 are attached together via spacers 65 . Then, a liquid crystal material is injected between the alignment controlling elements 50 .
  • liquid crystal material liquid crystal MLC6609 (MERCK&CO., Inc.) having a negative ⁇ is used. Thus, a sample device having the structure as shown in FIG. 11A is produced.
  • each unit feature 51 is 0.5 ⁇ m; the angle B between one of the side walls and the substrate surface is 75°; the width W of the upper face is 0; and the width F of the gap between adjoining unit features 51 is 0.
  • Six sample devices (Nos. 1 to 6) the pitch P of whose unit features 51 is varied as shown in Table 1, are employed.
  • the angle A between the other side wall and the substrate surface varies in accordance with the pitch P.
  • a pretilt can be imparted to the liquid crystal layer when the pitch P of the unit feature 51 is about 10 ⁇ m or less.
  • the pitch P in order to obtain a sufficient pretilt, the pitch P must be reduced (e.g., 1 ⁇ m or less). The presumable reason is as follows.
  • the pitch P of the unit features 51 is large, as shown by the simulation result of FIG. 7A , the liquid crystal alignment which originates at the surface of the alignment controlling element 50 will be averaged out at a middle level along the thickness direction of the liquid crystal layer, so that these liquid crystal molecules are hardly tilted from the substrate normal direction.
  • the pitch P is reduced, as shown by the simulation result of FIG. 7B , a portion in which liquid crystal alignment is confined (disclinations) is created between adjoining unit features 51 , thus suppressing the averaging out of liquid crystal alignment.
  • the liquid crystal molecules will still be oriented so as to be tilted from the substrate normal direction.
  • each unit feature 51 has a triangular cross-sectional shape.
  • alignment uniformity of the liquid crystal layer when applying a low voltage (2 to 3V) to the liquid crystal layers of sample device Nos. 7 to 12 was evaluated by visual inspection. The results are shown in Table 2.
  • alignment uniformity is denoted to be either “good” ( ⁇ ), “slightly random” ( ⁇ ), or “random” (X).
  • the unit features have a sufficiently large height H, liquid crystal alignment can be confined within each region surrounded by undulation features, so that a substantially uniform pretilt can be imparted to the central molecules in the overall liquid crystal layer. Therefore, the central molecules can be tilted in a desired direction upon the application of a voltage.
  • width W of the upper face is varied by controlling the thickness of the photoresist layer to be patterned through interference exposure, as well as exposure time and development time.
  • the gap width F can be generally obtained as the gap width F is increased; however, once the gap width F equals 2 ⁇ m or more, the liquid crystal alignment will become averaged out along the thickness direction of the liquid crystal layer as shown by the simulation result of FIG. 7A , so that a pretilt can no longer be obtained in the liquid crystal layer.
  • each unit feature 71 has a triangular cross-sectional shape.
  • sample device Nos. 21 to 25 were formed by using an electron beam lithography apparatus.
  • alignment uniformity of the liquid crystal layer when applying a low voltage (2 to 3V) to the liquid crystal layers of sample device Nos. 21 to 25 was evaluated by visual inspection. The results are shown in Table 5.
  • alignment uniformity is denoted to be either “good” ( ⁇ ), “slightly random” ( ⁇ ), or “random” (X), similarly to Table 2.
  • the angle A is preferably equal to or greater than 45°.
  • a desired pretilt can be obtained in the liquid crystal layer.
  • an arbitrary pretilt pretilt angle, pretilt direction
  • the pretilt direction is determined by the tilting angles of the side walls of each unit feature 51 and the like, it will be appreciated that alignment division, e.g., MVA mode, can be easily realized by varying the shape of the unit features 51 in accordance with specific locations on the substrate surface.
  • Embodiment 2 of the present invention has a similar structure to that of Embodiment 1 as described with reference to FIGS. 11A and 11B , except for the following difference.
  • the alignment controlling element employed in Embodiment 1 includes a plurality of unit features each having an asymmetric cross-sectional shape. Therefore, in Embodiment 1, disclinations are caused by confining liquid crystal alignment within certain regions or spaces, by utilizing ruggednesses consisting of unit features.
  • the alignment controlling element of the present embodiment includes a plurality of columnar unit features each having side walls which are perpendicular to the substrate surface.
  • the present embodiment is advantageous in that the surface configuration of the alignment controlling element can be easily formed by using an exposure apparatus having a usual resolution (1 ⁇ m or less), such as a stepper.
  • the pretilt (pretilt angle, pretilt direction) imparted to the liquid crystal layer depends on the shape of the unit features of the alignment controlling element. In order to cause a pretilt, it is preferable that the shape and arrangement of the unit features satisfy the following two conditions.
  • each bottom face which is surrounded by the closest unit features does not have a symmetry axis of rotation in the substrate normal direction. Since the pretilt has directionality, if the bottom face has a symmetry axis of rotation in the substrate normal direction (as in the case of a circle or a regular triangle), the pretilt in the positive direction and the pretilt in the negative direction will be equivalent for any given pretilt angle. In other words, the pretilts in different pretilt directions cancel each other and average out, such that the liquid crystal molecules in the liquid crystal layer have a pretilt angle of 0° as a whole.
  • each columnar unit feature may itself be a shape which does not have a symmetry axis of rotation in the substrate normal direction (e.g., an isosceles triangle or a trapezoid).
  • a symmetry axis of rotation in the substrate normal direction e.g., an isosceles triangle or a trapezoid.
  • the height (dent depth) H of each unit feature of the alignment controlling element is about 0.5 times or greater than the pitch P of the unit features, as in the case of the other embodiments. If the height H of the unit features is smaller than about 0.5 times the pitch P, liquid crystal alignment may average out as described with reference to FIG. 7A , thus making it difficult to obtain a pretilt.
  • a preferable alignment controlling element which satisfies the above two conditions may be, for example, a triangular prism-based alignment controlling element 40 as shown in FIGS. 8C and 8D .
  • the alignment controlling element may have any of the structures exemplified in FIGS. 16A to 16D .
  • triangular-prism-like unit features 82 are arranged on the surface of a substrate 81 with interspaces between one another.
  • each unit feature is a quadrangular prism having a trapezoidal upper face.
  • triangular-prism-like unit features are arranged in a pattern different from those shown in FIG. 8C and FIG. 16A .
  • each unit feature is a pentagonal prism. In any of these structures, each unit feature does not need to be axisymmetric.
  • the pretilt angle and pretilt direction can be freely set by controlling the shape and/or arrangement of the unit features.
  • the shape and/or arrangement of the unit features can be easily changed based on the mask shape used at the time of exposure, as described below. Therefore, there is an advantage in that the selection of the pretilt angle and pretilt direction is not restricted by the production process.
  • a photoresist layer (thickness: e.g., 0.8 ⁇ m) is formed on the surface of the substrate 81 by spin-coating.
  • a glass substrate having a conductive film formed on its surface may be used as the substrate 81 .
  • THMR-IP3300 is used as the photoresist, for example.
  • the shape of the photoresist layer is processed by using an exposure apparatus which is usually employed for the production of liquid crystal display devices, thus forming triangular prism (unit features) 82 arranged as shown in FIG. 16A . More specifically, a mask is provided so as to cover regions of the photoresist layer surface to become upper faces of the unit features 82 , and the photoresist layer is exposed through such a mask. Thereafter, development for the photoresist layer is performed.
  • any other alignment controlling element structure e.g., the alignment controlling elements shown in FIGS. 16B to 16D
  • any other alignment controlling element structure can be formed by a method similar to the above.
  • the surface configuration of the alignment controlling element of the present invention has two-dimensional anisotropy. Specifically, it is preferable that at least the periods along the X and Y directions (assuming that these directions are perpendicular to each other) are different, or phase changes occur along these directions.
  • anisotropy of the alignment controlling element according to the present invention will be described with reference to FIGS. 16A and 16C .
  • a direction which is parallel to the substrate 81 and perpendicular to the pretilt direction occurring due to disclinations in the gaps (dents) between unit features is defined as the X direction
  • a direction which is parallel to the substrate 81 and perpendicular to the X direction is defined as the Y direction.
  • each cross-sectional shape will appear shifted along the X direction, with a pitch equal to 1 ⁇ 2 of a period Tx with which the unit features 82 are placed along the X direction.
  • the cross-sectional shape along the Y direction will also appear shifted at various points on the X direction.
  • the unit features 82 are arranged so that phase changes in the cross-sectional shape occur along the X and Y directions.
  • the period Tx of the unit features 82 along the X direction and a period Ty of the unit features 82 along the Y direction may be equal or different.
  • FIG. 16B the same is also true of the structure shown in FIG. 16B .
  • the phase of the cross-sectional shape along the X direction does not change at different points on the Y direction
  • the phase of the cross-sectional shape along the Y direction does not change at different points on the X direction.
  • the period Tx of the unit features 82 along the X direction is not equal to the period Ty of the unit features 82 along the Y direction.
  • the liquid crystal display device of the present embodiment has a similar structure to that of Embodiment 1 as described with reference to FIGS. 11A and 11B , except that the device of the present embodiment is an MVA mode liquid crystal display device employing an alignment controlling element which is divided into regions.
  • a pretilt direction can be arbitrarily set based on the ruggednesses on a surface which is in contact with the liquid crystal layer, and therefore MVA mode is relatively easy to realize.
  • the alignment controlling element is formed on a substrate (e.g., a quartz substrate) which has an alignment control region 92 of 60 mm ⁇ 60 mm, for example.
  • a substrate e.g., a quartz substrate
  • unit regions 90 each sized 300 ⁇ m ⁇ 100 ⁇ m are arranged to form an array of 200 ⁇ 600.
  • the alignment control region 92 is provided correspondingly to a display region of the display device, whereas each unit region 90 is provided correspondingly to each pixel of the display device.
  • each unit region 90 is halved both longitudinally and laterally, thus resulting in four “sub” regions 94 .
  • Each subregion 94 may correspond to one of the subpixels which compose a pixel.
  • a plurality of unit features are arranged in each subregion 94 .
  • the unit features may have the shape of any of the unit features described in Embodiments 1 and 2.
  • the unit features in the subregions 94 are arranged in such a manner that a pretilt in a different direction is imparted to each different subregion.
  • each subregion 94 With reference to FIGS. 18A and 18B , the arrangement of unit features in each subregion 94 will be described more specifically.
  • Unit features 96 shown in FIG. 18A are similar to the unit features of Embodiment 1 as described with reference to FIG. 12 , for example.
  • the unit features 96 in each subregion 94 are arranged so as to cause a pretilt in the direction of an arrow.
  • the subregions 94 are designed so that the direction in which the unit features are arranged (the X direction in FIG. 12A ) constitutes an angle of 90° with the said direction of every adjoining subregion 94 .
  • a pretilt in a different direction can be imparted to each different subregion.
  • Unit features 96 ′ shown in FIG. 18B are similar to the unit features of Embodiment 2, for example. Although each unit feature 96 ′ is exemplified as a triangular prism, it may alternatively be a pentagonal prism or any other shape. In this figure, too, the unit features 96 ′ in each subregion 94 are arranged so as to cause a pretilt in the direction of an arrow.
  • each unit region 90 By thus dividing each unit region 90 into four subregions 94 , a quadruple alignment division can be realized.
  • another alignment controlling element which is divided into similar regions may be used as a substrate opposing the alignment controlling element 90 , or a flat counter substrate having a vertical alignment film applied to its surface may be used.
  • the pretilt angle ascribable to the alignment controlling element 90 is substantially halved; therefore, it would be necessary to design the ruggednesses of the alignment controlling element 90 so as to produce a correspondingly greater pretilt angle.
  • the alignment controlling element 90 can be produced by undulating a photoresist layer (thickness: about 1 ⁇ m or more) by means of a mask exposure apparatus (stepper). Alternatively, as in the preceding embodiments, the alignment controlling element 90 may be produced by arbitrarily undulating a photoresist layer (thickness: about 1 ⁇ m or less), which is formed on a substrate surface, with an interference exposure apparatus or an electron beam lithography apparatus, for example.
  • the alignment controlling element of the present embodiment is not limited to the structures shown in FIGS. 18A and 18B , as long as the pretilt direction caused by each unit feature of the ruggednesses is predetermined in accordance with a specific location of that unit feature on the substrate surface.
  • Each unit region 90 may be divided into strip-like subregions. Other methods of dividing the unit region 90 are illustrated in FIGS. 19A , 19 B, and 19 C. Alternatively, without dividing each unit region 90 into subregions, alignment division may be realized by varying the direction in which the unit features 96 or 96 ′ are arranged in accordance with specific locations on the unit region 90 .
  • the unit features 96 or 96 ′ may be arranged so that the pretilt direction within each unit region 90 is varied so as to constitute a so-called continuous pinwheel alignment.
  • the size of the unit region 90 , the number and shape of subregions, etc. may be arbitrarily set. It is preferable that the size of the unit region 90 corresponds to the size of each pixel in the display device.
  • the size and pitch of the unit features 96 or 96 ′ may also be arbitrarily set.
  • Embodiment 4 of the present invention differs from Embodiments 1 to 3 in that an alignment controlling element has a surface formed through emboss.
  • the alignment controlling element is formed by undulating a resin layer (photoresist layer).
  • the resin layer is required to have a high enough photosensitivity to support high resolution, thus imposing limitations on heat resistance and solvent endurance. Since the material of the resin layer cannot be freely selected, the electrical properties of the resin layer material, such as dielectric constant, electrical conductivity, and impurity concentration, are constrained. This leads to a problem in the production process in that, when applying a vertical alignment film to the resin layer surface whose shape has been processed, for example, the solvent and the firing temperature for the vertical alignment film must be selected so as not to damage the resin layer surface. Moreover, since ruggednesses to a height of about 1 ⁇ m are formed on the resin layer surface toward the interior of the liquid crystal layer, a voltage drop may be caused by the ruggednesses, or impurities may be eluted from the resin layer.
  • ruggednesses are formed on the alignment controlling element by emboss process.
  • a method of formation is referred to as a “replica technique”.
  • FIG. 20A a master 101 having ruggednesses formed on its surface is produced.
  • a substrate 102 on whose surface a resin material 103 for replication has been applied or dropped is prepared.
  • the master 101 is pressed against the surface of the substrate 102 to emboss the surface configuration of the master 101 onto the resin material 103 .
  • FIG. 20B an alignment controlling element 105 with a resin layer 103 ′ having a shape that corresponds to the ruggednesses of the master 101 is obtained.
  • the resin layer does not need to have a high photosensitivity, so that the resin layer material can be selected with a greater freedom. As a result, a high-performance and highly reliable display device can be obtained.
  • a master 101 having an undulated surface is produced.
  • the master 101 can be produced by, after forming a photoresist layer on a substrate, patterning the photoresist layer by using a double beam interference exposure apparatus, an electron beam lithography apparatus, or a mask exposure apparatus such as a stepper.
  • the method for patterning the photoresist layer may be the same as that described in Embodiment 1 or 2, for example.
  • the master 101 can be produced by mechanically grinding a substrate composed of Al or other materials, or etching a monocrystalline substrate-such as an Si substrate.
  • the master 101 does not need to be optically transparent, but may be formed of any material which permits micromachining. As a material which permits micromachining, a high resolution resist may be used, for example.
  • a resin material 103 is applied to the surface of the transparent substrate 102 , and thereafter the master 101 is attached to the transparent substrate 102 in such a manner that the ruggednesses of the master 101 are in contact with the resin material 103 .
  • the transparent substrate 102 for example, a glass substrate, or a glass substrate having a conductive film (ITO) on its surface may be used.
  • the resin material 103 a UV (ultraviolet)-curable resin is used herein.
  • the resin material 103 may be composed of any other resin material such as a thermoplastic resin or a thermosetting resin.
  • the attachment of the transparent substrate 102 to the master 101 can be performed by using an apparatus as shown in FIG. 22 , for example.
  • the transparent substrate 102 is placed on a lower stage (a sample stage made of quartz glass) 107
  • the master 101 is placed on an upper stage (a sample stage made of quartz glass) 109 .
  • the master 101 and the transparent substrate 102 are attached together via the resin material 103 .
  • the substrate 102 having the master 101 attached thereto is held for a predetermined period of time while being pressed in the directions of the arrows.
  • the resin material 103 is irradiated with ultraviolet by using an ultraviolet lamp 106 .
  • the resin material 103 sets, and becomes a resin layer 103 ′.
  • the upper stage 109 is elevated to take the master 101 off the substrate 102 .
  • an alignment controlling element 105 having the undulated resin layer 103 ′ is obtained.
  • the method for producing an alignment controlling element according to the present embodiment is not limited to the above.
  • a roller-like master may be produced, and the side face configuration of the roller-like master may be embossed onto a resin layer.
  • the emboss may be performed by using an apparatus shown in FIG. 23 , for example. A specific example of this emboss method will be illustrated below.
  • the substrate 102 is placed on a stage 108 of the apparatus shown in FIG. 23 .
  • the resin material 103 is applied to the surface of the substrate 102 .
  • the resin material 103 is a UV-curable resin.
  • a roller-like master 110 being rotated in the direction of an arrow 111 is pressed against the substrate 102 , while the stage 108 is moved in the direction of an arrow 112 .
  • a portion of the resin material 103 where the master 110 is pressed against can be irradiated with ultraviolet from an ultraviolet lamp 113 , through an opening 114 for permitting ultraviolet irradiation.
  • the resin material 103 is consecutively set, whereby the undulated resin layer 103 ′ is formed.
  • emboss process may be performed for a thermoplastic resin (resin material for replication) 103 , for example.
  • a thermoplastic resin resin material for replication
  • the substrate 102 and the thermoplastic resin 103 are previously heated, and the master 110 is pressed against the thermoplastic resin 103 . Thereafter, the thermoplastic resin 103 is allowed to cool and set.
  • the apparatus shown in FIG. 23 can be used, with a heating and cooling mechanism added thereto.
  • the side face configuration of the roller-like master 110 can be embossed (or otherwise transferred) with a method similar to intaglio printing.
  • an apparatus shown in FIG. 24 can be used, for example. A specific example of this emboss method will be illustrated below.
  • the substrate 102 is placed on a stage 123 .
  • the resin material 103 is placed in a container 120 .
  • the resin material 103 is continually discharged through an opening in the bottom face of the container 120 , so as to be applied to the surface of an application roller 121 , which is being rotated in the direction of an arrow 124 .
  • the resin material 103 having been applied to the application roller 121 is uniformly applied to the surface of a master 110 , which is being rotated in the direction of an arrow 125 .
  • the master 110 having the resin material 103 applied thereto is pressed against the substrate 102 being placed on the stage 123 .
  • the stage 123 moves in the direction of an arrow 126 in synchronization with the rotation of the master 110 .
  • the resin material 103 which has been applied to the master 110 is transferred (embossed) onto the substrate 102 , whereby a desired fine configuration composed of the resin material 103 is formed on the substrate 102 .
  • the resin material 103 which has been transferred onto the substrate 102 is allowed to set via ultraviolet irradiation or heating, thus becoming a resin layer 103 ′.
  • the master is directly pressed against the substrate 102 such as a glass substrate, and is likely to be reused multiple times. Therefore, the master is likely to be grazed. If a grazed master is used for continued emboss, the grazes may themselves be embossed. Therefore, one possible method is to first emboss the surface configuration of a master onto a film, and then emboss this configuration further onto a resin material by using the film as a master.
  • the film will be referred to a “embossed master”.
  • an apparatus shown in FIG. 25 can be used, for example. A specific example of this emboss method will be illustrated below.
  • the substrate 102 is placed on the back side of a stage 128 .
  • a film (thickness: 0.5 ⁇ m or more) 127 which is composed of a material which can be deformed with heat is supplied between the master 110 and a press roller 129 , thus forming fine ruggednesses on the film 127 .
  • the film 127 may be PET, for example.
  • the resin material 103 which is contained in a container 120 is thinly applied to the film 127 having the ruggednesses formed thereon.
  • the resin material 103 thus applied is transferred (embossed) onto the substrate 102 placed on the back side of the stage 128 , by the action of a peeling roller 130 .
  • the resin material 103 having been transferred onto the substrate 102 is allowed to set via ultraviolet irradiation or heating, thus becoming the resin layer 103 ′.
  • the master 110 is prevented from being damaged through a plurality of emboss processes.
  • the resin material 103 may be applied to the film 127 by means of an application roller.
  • the resin material 103 which has been applied to the film 127 may be allowed to set to a certain degree via ultraviolet irradiation or heating, before being transferred onto the substrate 102 .
  • the liquid crystal display device of the present embodiment is an MVA mode display device having an alignment controlling element which is divided into a plurality of subregions.
  • the alignment controlling element has a plurality of unit regions which may correspond to the pixels of a display device.
  • each unit region is divided into a plurality of subregions. Each of these subregions imparts a different pretilt to each subpixel.
  • Each unit region of the alignment controlling element of the present embodiment is divided into a plurality of subregions according to one of the preferred patterns described below. Note that the below-described division patterns for the alignment controlling element can also be adopted for the master in Embodiment 4, or the alignment controlling element of Embodiments 1 to 3.
  • liquid crystal molecules incline upon the application of a voltage in VAN mode, thus realizing a white display state due to their birefringence. Since a liquid crystal cell is interposed between a pair of polarizers 10 whose absorption axes constitute an angle of 90° with each other, it is preferable that the direction in which the liquid crystal molecules incline (pretilt direction) and the absorption axis of each polarizer 10 each constitute an angle of 45° on the substrate surface, for an efficient utilization of birefringence.
  • the number of subregions (division number) in a single unit region is two or four, the subregions being equal in area. Note that it is only preferable that the subregions in each given pixel be equal. The area of a subregion in one pixel may well be different from the area of a subregion in another pixel.
  • Possible division patterns for the unit region that can satisfy the first and second conditions above are patterns in which the unit region is divided into four subregions (I) to (IV) as shown in FIGS. 19A to 19C , for example.
  • Any such division pattern can be applied to one or both of the pair of opposing substrates of a display device between which a liquid crystal layer is interposed. Exemplary applications of such division patterns will now be described with reference to FIGS. 26A to 26C .
  • FIGS. 26A to 26C each illustrate a portion of a liquid crystal layer 142 and a portion of a pair of substrates 141 and 143 corresponding to a single pixel of a display device.
  • a vertical alignment type liquid crystal layer 142 is provided between the first substrate 143 and the second substrate 141 .
  • the first substrate 143 is a color filter substrate
  • the second substrate 141 is a TFT substrate.
  • the second substrate 141 may alternatively be a color filter substrate and the first substrate 143 may be a TFT substrate.
  • ruggednesses are formed in the same or different division pattern.
  • ruggednesses with a certain division pattern may be formed on the surface of only one of the substrates.
  • ruggednesses are formed on the surface of each of the first substrate 143 and the second substrate 141 .
  • the unit region of these substrates 143 and 141 has subregions (I) to (IV) and subregions (I′) to (IV′), respectively, as divided in accordance with the pattern shown in FIG. 19B . Therefore, one pixel is divided into four subpixels which are defined by the opposing subregions (I) and (I′); (II) and (II′); (III) and (III′); and (IV) and (IV′).
  • ruggednesses having subregions (I) to (IV) as divided in accordance with the pattern shown in FIG. 19B are formed only on the surface of the second substrate 141 .
  • the unit region (V′) of the first substrate 143 has a flat surface, which structure cannot produce a pretilt. Therefore, each pixel is divided into four subpixels as defined by the subregions (I) to (IV) and the unit region (V′).
  • ruggednesses with a division pattern are formed on only one substrate 141 , while ruggednesses are formed on the other substrate 143 , so that the production process can be shortened.
  • the pretilt angle imparted to the central molecules in the liquid crystal layer 142 would be half of the pretilt angle imparted to the central molecules in the liquid crystal layer 142 shown in FIG. 26A .
  • ruggednesses which are divided in accordance with the pattern shown in FIG. 19B are formed on the face of a substrate which is in contact with the liquid crystal layer.
  • ruggednesses which are divided in accordance with the pattern shown in FIG. 19A or 19 C, or any other pattern may instead be formed.
  • ruggednesses are formed on the surface of each of the first substrate 143 and the second substrate 141 , where the unit region of the substrates 143 and 141 is divided, respectively, into two subregions (III′) and (IV′) and two subregions (I) and (II).
  • the subregions of the first substrate 143 are offset from the subregions of the second substrate 141 by 1 ⁇ 2 of the subregion pitch, with the liquid crystal layer 142 interposed therebetween.
  • the subregion (II) opposes the two subregions (III′) and (IV′).
  • one pixel is divided into four subpixels as defined by the subregions (I) and (III′); subregions (II) and (III′); subregions (II) and (IV′); and subregions (I) and (IV′).
  • the area of each of the subregions (I), (II), (III′) and (IV′) is twice the area of each subregion shown in FIG. 26A . Therefore, even in the case where the division into regions can only be performed with a relatively low resolution, the first substrate 143 and the second substrate 141 in this example can be adequately produced.
  • Alignment division can be realized in any of the examples shown in FIGS. 26A to 26C . However, for the sake of the production process, it is preferable to provide ruggednesses on only one of the substrates, as shown in FIG. 26B . The reason is that, as described above, the formation of minute ruggednesses is likely to complicate the production process of the display device.
  • the division pattern for the unit region in MVA mode must be such that each pixel is split into subregions of exactly the same area, so that the same amount of brightness change will result when the viewing direction is inclined in any of the upper/lower/right/left directions.
  • the positions of the subregions and the order in which they are positioned do not affect displaying. Therefore, it is advantageous to form consecutive groups of subregions (subregion groups) on the master, where size of the subregions and unit region are selected so that one unit region includes a plurality of subregions.
  • the total area of subregions of one subregion group is substantially equal to the total area of subregions of another subregion group.
  • Each liquid crystal display device includes a plurality of pixels arranged in a matrix of rows and columns. Typically, gate lines and CS lines are provided in the row direction, and source lines are provided in the column direction.
  • a TFT substrate of the liquid crystal display device has an alignment controlling structure (ruggednesses) which is formed by using the aforementioned master.
  • FIG. 27A is an enlarged plan view showing three pixels of an active matrix type liquid crystal display device of a common type.
  • FIG. 27B is a perspective view showing one pixel of the liquid crystal display device shown in FIG. 27A .
  • each pixel has a rectangular shape which is elongated in the column direction.
  • each pixel includes a portion of: a TFT substrate 910 ; a color filter substrate 911 ; and a liquid crystal layer 908 interposed between the substrates 910 and 911 .
  • a transparent electrode 905 is formed on the face of the color filter substrate 911 facing the liquid crystal layer.
  • a pixel electrode 906 and a switching element (TFT) 903 are provided for each pixel.
  • the switching element 903 is connected to a gate line 901 and a source line 902 .
  • a CS line 904 is provided across a middle portion of each pixel.
  • a region of the pixel through which light can be transmitted defines an aperture denoted as “ 201 ”. Therefore, ruggednesses which are located in the aperture 201 most effectively exhibit a liquid crystal alignment controlling function.
  • the aperture is a rectangle having a shorter side which is parallel to the row direction and a longer side which is parallel to the column direction.
  • each split, stripe-like subregion is parallel to the shorter sides or the longer sides of the aperture 201 . Therefore, the effective area (i.e., the area which contributes to alignment control) of the subregion overlapping with the perimeter of the aperture 201 is reduced by the CS line 904 and the gate line 901 . As a result, the ratio between total effective areas of the respective subregions is likely to become unbalanced. Moreover, the amounts of decrease in the effective areas of the subregions will depend on an interspace Ws with an adjoining aperture.
  • FIG. 28 an exemplary structure shown in FIG. 28 will be described.
  • an alignment controlling structure which is split into stripe-like regions obliquely traversing an aperture 201 is formed.
  • the ratio between total effective areas of the respective subregions can be substantially improved.
  • pixels are formed such that a height H p of the aperture 201 is an integer multiple of a width W p of the aperture (eq.(1)).
  • H p nW p (where n is an integer other than 0) eq.(1)
  • the angle ⁇ is 45°.
  • m in eq.(3) is “1”, for example, the total areas of the respective subregions can be made always equal, irrespective of any mispositioning between the master pattern and the substrate onto which the ruggednesses are to be embossed, by setting the size (H p , W p ) of the pixels and the pitch GP of the subpixel groups so that eq.(1′) and eq.(3′) are satisfied, and embossing so that the angle ⁇ is 45°.
  • the ratio between effective areas of the subregions can be kept equal irrespectively of the position and width Wcs of the CS line 904 across the middle portion of the pixel, and the size of the interspace Ws between adjoining pixel apertures.
  • a display device includes: first and second substrates, each having an alignment controlling structure divided into regions as shown in FIG. 26A ; and a liquid crystal layer interposed between the substrates.
  • the alignment controlling structures on the first and second substrate surfaces are formed by the replica technique which has been described with reference to FIGS. 21A to 21D .
  • Example 1 a method for producing the display device of Example 1 will be described more specifically.
  • a master having ruggednesses composed of a plurality of unit features is produced.
  • the ruggednesses on the master are formed by using a resist which has been applied to a glass substrate, in such a manner that the resin is subjected to four times of exposure by using a photomask, each time for each subregion, and then performing development.
  • the exposure is performed while changing the direction of exposure by 90° for each subregion.
  • the exposure for each subregion may be performed in the following two steps. For example, an exposure may be performed using a double beam interference exposure apparatus (first exposure), and thereafter a usual mask exposure (second exposure) may be performed.
  • the second exposure is performed for the purpose of forming a plurality of grooves in a direction perpendicular to the direction in which the unit features are arranged.
  • the grooves can be created by mask exposure because their pitch is relatively coarse.
  • a double beam interference exposure apparatus may be employed in the second exposure to perform an interference exposure in a direction different from the direction of the first exposure.
  • an interference exposure apparatus which is not equipped with a prism, and simultaneously irradiate the resist on the glass substrate with two different laser beams. In this case, the interference fringes ascribable to the respective laser beams can be independently controlled.
  • Unit features of the resultant ruggednesses are similar to those described in Embodiment 1.
  • the unit features have a pitch P of 0.5 ⁇ m; the width W of the gap between adjoining unit features is 0; the height H of each unit feature is 0.5 ⁇ m; the side wall angles A and B are 105° and 75°, respectively; and the width F of the upper face is 0.
  • the grooves are formed with a pitch PG of 5 ⁇ m along a direction perpendicular to the direction in which the unit features are arranged, and each groove has a width G of 1 ⁇ m. It should be understood that the values of the above parameters P, W, H, A, B, F, PG, G are approximate.
  • the surface configuration of the resultant master is embossed to a substrate surface.
  • the emboss is performed by using the apparatus shown in FIG. 22 .
  • the master is pressed against a substrate having a UV-curable resin (1 ⁇ m) applied thereto by spin-coating, with a pressure of 35 Kg/cm 2 , and left pressed for 60 second.
  • the UV-curable resin is irradiated with ultraviolet (0.7 J/cm 2 ), whereby the UV-curable resin sets and becomes a resin layer having ruggednesses formed on its surface.
  • the master is removed from the substrate.
  • a vertical alignment film is formed on the surface of the resin layer by spin-coating. As a result, a first substrate is obtained.
  • a second substrate is also produced by a similar method.
  • the first and second substrates thus obtained are placed so as to oppose each other as shown in FIG. 26A , with the vertical alignment films facing inward, and are attached together while leaving an interspace of 3 ⁇ m therebetween. Between these substrates, a liquid crystal (MLC6609) having a negative ⁇ is injected. Thus, the display device of Example 1 is completed.
  • MLC6609 liquid crystal having a negative ⁇
  • the central molecules are vertically aligned in the absence of an applied voltage across the liquid crystal layer, with a tilt (pretilt) from the substrate normal direction. It can also be confirmed that, when a voltage is applied across the liquid crystal layer, the liquid crystal alignment is divided into four regions, in which the liquid crystal molecules incline in respectively different directions as shown in FIG. 1 .
  • Example 1 illustrates a case where a master is produced by utilizing double beam interference exposure or the like
  • similar effects to those in Example 1 can also be obtained by producing a master having unit features similar to those of Embodiments 1 and 2 formed by using an electron beam lithography apparatus, a stepper, or the like.
  • a display device includes: first and second substrates, each having an alignment controlling structure formed on its surface; and a liquid crystal layer interposed between the substrates.
  • Each subregion group consists of four subregions (I), (II), (III), and (IV).
  • the pixel size (width W p , height H p ) and the pitch GP of the subregion group are set so as to satisfy eq.(1′) and eq.(3′) above.
  • the ruggednesses on the surfaces of the first and second substrates are formed by the replica technique which has been described with reference to FIGS. 21A to 21D .
  • Example 2 a method for producing the display device of Example 2 will be described more specifically.
  • a master having ruggednesses composed of a plurality of unit features is produced.
  • the ruggednesses on the master are formed by a method similar to that used in Example 1, by using double beam interference exposure and mask exposure.
  • subregion groups pitch GP: 100 ⁇
  • the directions of the unit features in each subregion are prescribed so that a constant pretilt direction exists due to ruggednesses within each subregion, and that the pretilt directions ascribable to the ruggednesses in adjoining subregions differ by 90° on the substrate surface.
  • the unit features in each subregion are similar to those in Embodiment 1.
  • the unit features have a pitch P of 0.5 ⁇ m; the width W of the gap between adjoining unit features is 0; the height H of each unit feature is 0.5 ⁇ m; the side wall angles A and B are 105° and 75°, respectively; and the width F of the upper face is 0.
  • the grooves are formed with a pitch PG of 5 ⁇ m along a direction perpendicular to the direction in which the unit features are arranged, and each groove has a width G of 1 ⁇ m.
  • a TFT substrate as shown in FIG. 23 is prepared.
  • the width W p of each pixel is 100 ⁇ m; the height H p of each pixel is 300 ⁇ m; the width Wcs of each CS line is 20 ⁇ m; and the width Ws of the interspace between adjoining apertures is 30 ⁇ m.
  • the surface configuration of the resultant master is embossed to the surface of the TFT substrate.
  • the emboss is performed by using the apparatus shown in FIG. 22 .
  • the master is pressed against a substrate having a UV-curable resin (1 ⁇ m) applied thereto by spin-coating, with a pressure of 35 Kg/cm 2 , and left pressed for 60 second.
  • the UV-curable resin is irradiated with ultraviolet (0.7 J/cm 2 ), whereby the UV-curable resin sets and becomes a resin layer having ruggednesses formed on its surface.
  • the master is removed from the substrate.
  • a vertical alignment film is formed on the surface of the resin layer by spin-coating.
  • a TFT substrate having an alignment controlling structure formed thereon is obtained.
  • a counter substrate (first substrate) is also produced by a similar method.
  • the first and second substrates thus obtained are placed so as to oppose each other with the vertical alignment films facing inward, and are attached together while leaving an interspace of 3 ⁇ m therebetween. Between these substrates, a liquid crystal (MLC6609) having a negative ⁇ is injected. Thus, the display device of Example 2 is completed.
  • MLC6609 liquid crystal having a negative ⁇
  • the central molecules are vertically aligned in the absence of an applied voltage across the liquid crystal layer, with a tilt (pretilt) from the substrate normal direction. It can also be confirmed that, when a voltage is applied across the liquid crystal layer, the liquid crystal alignment is divided into four regions, in which the liquid crystal molecules incline in respectively different directions. Since the total areas of the respective subregions (I) to (IV) within each pixel are substantially equal, the same amount of brightness change results when the viewing direction is inclined in any of the upper/lower/right/left directions, thus providing excellent viewing angle characteristics.
  • Example 2 illustrates a case where a master is produced by utilizing double beam interference exposure or the like
  • similar effects to those in Example 2 can also be obtained by producing a master having unit features similar to those of Embodiments 1 and 2 formed by using an electron beam lithography apparatus, a stepper, or the like.
  • the liquid crystal display device of the present embodiment is an MVA mode display device having an alignment controlling element which is divided into a plurality of subregions.
  • the liquid crystal display device of the present embodiment differs from the liquid crystal display device of any other embodiment above in that each subregion is further divided into a plurality of minute regions.
  • alignment division for realizing different pretilt directions is performed by dividing a unit region (corresponding to a pixel) into subregions.
  • each subregion is divided into a plurality of minute regions, each of which causes a pretilt in the same direction (pretilt direction) but at a different angle (pretilt angle).
  • FIG. 29 is a graph a showing light transmittance Tr when a voltage V is applied across a liquid crystal layer.
  • the transmittance Tr shifts toward lower voltages. This is because, even assuming that the tilting direction (pretilt direction) is the same, the tendency to incline in the polar angle direction in response to an applied voltage varies depending on the initial pretilt angle.
  • the liquid crystal layer will, upon the application of a voltage, not only have regions in which liquid crystal molecules incline in different directions, but also regions in which liquid crystal molecules incline (in the same direction but) at different tilt angles (i.e., angles in the direction in which liquid crystal molecules will rise). These regions are averaged out so that any change in brightness and contrast which occurs when the viewing direction is changed is milder than in conventional cases.
  • the alignment division realized by the present embodiment is unprecedented in that different pretilt angles are imparted to liquid crystal molecules which are located near a middle level along the thickness direction of the liquid crystal layer.
  • the presumable reason for the lack of precedents is the difficulty in forming an alignment controlling structure by performing an alignment treatment with an increased precision.
  • each subregion is divided into a plurality of minute regions, such that unit features of a different shape are arranged in each different minute region.
  • FIGS. 30A and 30B are perspective views illustrating exemplary subregion constructions according to the present embodiment.
  • a subregion 210 shown in FIG. 30A is divided into two minute regions 220 a and 220 b .
  • unit features 212 a and 212 b having a triangular cross section are arranged, with substantially the same pitch P.
  • Both minute regions 220 a and 220 b realize the same pretilt direction.
  • a side wall angle 213 a of each unit feature 212 a in the minute region 220 a is smaller than a side wall angle 213 b of each unit feature 212 b in the minute region 220 b . Therefore, the minute region 220 a realizes a different pretilt angle from that realized by the minute region 220 b.
  • a subregion 240 shown in FIG. 30B is divided into two minute regions 230 a and 230 b .
  • minute regions 230 a and 230 b respectively, triangular-prism-like unit features 231 a and 231 b are arranged, with substantially the same pitch P.
  • the height of an isosceles triangle constituting the upper face of each unit feature 231 a in the minute region 230 a is different from the height of an isosceles triangle constituting the upper face of each unit feature 231 b in the minute region 230 b . Therefore, although both minute regions 230 a and 230 b realize the same pretilt direction, the minute region 230 a realizes a different pretilt angle from that realized by the minute region 230 b.
  • FIG. 31A is a diagram illustrating an exemplary construction of a unit region in the alignment controlling element.
  • a unit region 250 shown in FIG. 31A is divided into four subregions (I), (II), (III), and (IV). Each subregion has the structure shown in FIG. 30A or 30 B, for example. In other words, the subregion (I) is divided into two minute regions Ia and Ib. The other subregions (II) to (IV) are similarly divided into two minute regions IIa and IIb, IIIa and IIIb, and IVa and IVb, respectively.
  • the area ratio between the two minute regions included in each subregion is shown to be 1:1. Note, however, that the area ratio between the minute regions may be optimized in accordance with the viewing angle characteristics, and it is not necessary that the minute regions included in each subregion be equal in area.
  • the pattern of dividing the unit region into subregions and the pattern of dividing each subregion into minute regions are not limited to those exemplified in FIG. 31A , but may be arbitrarily chosen.
  • the alignment controlling element of the present embodiment can be formed by a method similar to those used in the other embodiments.
  • the alignment controlling element of the present embodiment is formed by a replica technique.
  • a liquid crystal display device includes first and second substrates, and a liquid crystal layer interposed between these substrates.
  • the first substrate color filter substrate
  • the ruggednesses on the surface of the second substrate are such that, as shown in FIG. 31A , each unit region is divided into four subregions (I) to (IV), each subregion being further divided into two minute regions Ia and Ib, IIa and IIb, IIIa and IIIb, and IVa and IVb.
  • the subregions (I) to (IV) are equal in area.
  • the area ratios Ia:Ib, IIa:IIb, IIIa:IIIb, IVa:IVb between the minute regions in each subregion are all 1:4.
  • each subregion as shown in FIG. 30A , unit features having a triangular cross section are arranged.
  • the pitch P of the unit features is 0.5 ⁇ m; the width W of the gap between adjoining unit features is 0; and the width F of the upper face is 0.
  • the height H of each unit feature and the side wall angles A and B are prescribed so that the liquid crystal molecules at the interface between the substrate and the liquid crystal layer have a tilt angle (i.e., angles to which the liquid crystal molecules will rise) of 89°.
  • the height H of each unit feature and the side wall angles A and B are prescribed so that the liquid crystal molecules at the interface between the substrate and the liquid crystal layer have a tilt angle of 85°.
  • grooves are provided in a direction perpendicular to the direction in which the unit features are arranged, with a pitch GP of 5 ⁇ m. The width of each groove is 1 ⁇ m.
  • the liquid crystal display device of Example 3 may be produced as follows.
  • a roller-like master having predetermined ruggednesses formed on its surface is produced, and the surface configuration of the master is embossed onto a UV-curable resin which has been applied on a substrate surface.
  • a resin layer having a structure corresponding to the ruggednesses on the master is formed on a TFT substrate.
  • the emboss is performed by using the apparatus shown in FIG. 25 .
  • a vertical alignment film is formed on the surface of the resin layer by spin-coating.
  • the TFT substrate having the resin layer formed thereon and a color filter substrate having a vertical alignment film formed on its surface are placed so as to oppose each other with the vertical alignment films facing inward, and are attached together while leaving an interspace of 3 ⁇ m therebetween. Between these substrates, a liquid crystal (MLC6609) having a negative ⁇ is injected. Thus, the display device of Example 3 is completed.
  • MLC6609 liquid crystal
  • the actual light transmittance measurement for each minute region is described below.
  • the transmission axes of the polarizers are in vertical and horizontal directions.
  • FIG. 31B shows the frontal transmittance
  • FIG. 31C shows the transmittance obtained when viewed at an azimuth angle 45° (45° in the upper right direction) and a viewing angle 60° (i.e., 60° from the substrate normal direction), of the minute regions Ia to IVa, and Ib to IVb.
  • the liquid crystal display device of the present embodiment includes a pair of opposing substrates, and a liquid crystal layer interposed therebetween.
  • One or both of the pair of substrates is constructed by using an alignment controlling element 501 shown in FIG. 32A .
  • the alignment controlling element 501 includes a substrate 502 , and a plurality of unit features 503 formed on the surface of the substrate 502 , and can function as an alignment controlling means for controlling the orientations of the liquid crystal molecules contained in a liquid crystal layer 510 .
  • the liquid crystal layer 510 is a vertical alignment type liquid crystal layer in which a negative type nematic liquid crystal ( ⁇ 0) is employed.
  • Each of the unit features 503 formed on the surface of the alignment controlling element 501 is composed of a wall member 505 and a slope member 507 .
  • the wall member 505 includes two side faces 505 a and 505 b and a ridge 505 r formed by these side faces.
  • the slope member 507 is formed so as to be in contact with one side face 505 a of the wall member 505 .
  • the slope member 507 has a slanted face 507 a , which is slanted with respect to the surface of the substrate 502 .
  • the wall member 505 and the slope member 507 are typically composed of different materials.
  • the wall member 505 of FIG. 32A is shown to have a substantially triangular cross-sectional shape, the wall member 505 may alternatively have a curved cross-sectional shape or any other (e.g., a quadrangular) cross-sectional shape.
  • FIG. 32B is an exemplary plan view of the alignment controlling element 501 .
  • the alignment controlling element 501 includes the unit features 503 , which appear as relatively short strips arranged in the direction of the ridges 505 r (hereinafter the “Y direction”) with predetermined grooves 504 left therebetween.
  • the unit features 503 may be arranged in parallel to a direction perpendicular to the Y direction (hereinafter the “X direction”).
  • FIG. 32B shows the X direction to be perpendicular to the Y direction, the X direction may be any direction different from the Y direction. Note that, in the present embodiment, the unit features 503 do not need to be periodically arranged.
  • each liquid crystal molecule located at the surface of the slanted face 507 a is oriented substantially perpendicularly to each slanted face 507 a of the alignment controlling element 501 . Therefore, the liquid crystal molecules in the liquid crystal layer 510 are tilted from the normal direction of the surface of the substrate 502 (pretilt direction).
  • pretilt direction the normal direction of the surface of the substrate 502
  • each liquid crystal molecule will try to incline in the pretilt direction. If the applied voltage is sufficiently high, the liquid crystal molecules will lie substantially parallel to the surface of the substrate 502 , with the longer axes of the liquid crystal molecules being aligned in the direction of the grooves 504 .
  • the unit features 503 have an average pitch of 0.1 ⁇ m or more.
  • the unit features 503 have an average pitch of 10 ⁇ m or less.
  • the “(average) pitch of unit features” is defined to be a distance between adjoining wall members, as taken between the apices of the side faces which are in contact with the associated slope members, in the plane of the substrate surface.
  • the pitch of the unit features shown in FIG. 33A is a distance P X between the highest points 505 p of the side faces 505 a of any two adjoining wall members 505 (the side faces 505 a being in contact with their associated slope members 507 ), as taken in the plane of the substrate surface.
  • the pitch of the unit features is, as shown in FIG. 33B , a distance P X between the highest points 506 p of the side faces 506 a of any two adjoining wall members 506 , as taken in the plane of the substrate surface.
  • a pitch P Y of the unit features 503 along the direction of the ridges 505 r is, for example, no less than 0.1 ⁇ m and no more than 10 ⁇ m.
  • Each groove has a width of e.g. no less than 10 nm, which is equal to or less than the pitch P X of the unit features 503 along the X direction.
  • the unit features 503 have a height (which herein is the height of the wall members 505 ) which is no less than 10 nm and no more than 10 ⁇ m. If the height is no less than 10 nm, the surface configuration of the alignment controlling element 501 can securely restrict the liquid crystal molecule orientations. On the other hand, if the height is no more than 10 ⁇ m, any problems associated with the effective thickness of the liquid crystal layer 510 being changed by the presence of the unit features 503 can be suppressed.
  • the angle between the slanted face 507 a of each unit feature 503 and the surface of the substrate 502 can be arbitrarily selected, in the range of greater than 0° and no more than 45°, for example.
  • the liquid crystal molecules can be oriented so as to be tilted from the normal direction of the substrate 502 by an angle of no less than 10° and no more than 45°, in the neighborhood of the slanted faces 507 a of the alignment controlling element 501 .
  • each slope member 507 of the present embodiment may fail to become planar as shown in FIGS. 33C and 33D , for reasons associated with the method by which they are produced, etc. In such cases, as shown in FIGS.
  • a line 507 A is drawn between the highest point 505 p of the side face 505 a of the wall member 505 (the side face 505 a being in contact with the slope member 507 ) and a point 507 c at which the slanted face 507 a of the slope member 507 comes in contact with the substrate surface; and an angle a 1 between this line 507 A and the substrate surface will be regarded as the “slanted face angle”.
  • the side face 505 b which is not in contact with the slope member 507 preferably constitutes, with the surface of the substrate 502 , an angle which is greater than the aforementioned angle a 1 between the slanted face 507 a and the surface of the substrate 502 .
  • the angle between the side face 505 b of the wall member 505 and the surface of the substrate 502 is typically greater than 45° and less than 180°. As shown in FIG.
  • the angle between the side face 505 b of the wall member 505 and the surface of the substrate 502 is defined as an angle a 2 between the substrate surface and a line 505 B which is drawn between the highest point 505 p ′ of the side face 505 b of the wall member 505 and a point 505 c at which the side face 505 b comes in contact with the substrate surface.
  • the liquid crystal molecules located at the interface between the surface of the alignment controlling element 501 and the liquid crystal layer are oriented along the normal direction of the surface of the alignment controlling element 501 .
  • the liquid crystal molecules located on each slanted face have a pretilt (first pretilt) along the normal direction of the slanted face 507 a
  • the liquid crystal molecules located on the side face of each wall member have a pretilt (second pretilt) along the normal direction of the side face 505 b of the wall member.
  • each unit feature 503 has an asymmetric cross section, and the pretilt which is imparted by the slanted face 7 a is predominant over the pretilt which is imparted by the side face 5 b of the wall member. Therefore, the liquid crystal molecules located near a middle level along the thickness direction of the liquid crystal layer are more susceptible to the first pretilt imparted by the slanted face 507 a , so that the liquid crystal molecules will have the same pretilt direction as that of the first pretilt and a smaller pretilt angle than that of the first pretilt, for example.
  • pretilt of the liquid crystal molecules located near a middle level along the thickness direction of the liquid crystal layer are affected not only by the surface configuration of the alignment controlling element 501 , but also by the surface configuration of the counter substrate which is in contact with the upper face of the liquid crystal layer 510 .
  • the exposed surface of the unit features 503 of the alignment controlling element 501 shown in FIG. 32A is in contact with the liquid crystal layer 510 , it is not necessary that they are in contact with each other.
  • a vertical alignment film and/or a conductive film which can function as an electrode for applying a voltage to the liquid crystal layer 510 or a multilayer film having a conductive film and an alignment film stacked in this order may be provided. It is desirable that any film provided between the alignment controlling element 501 and the liquid crystal layer 510 is sufficiently thin so that the film can acquire a surface configuration which reflects the shape of the unit features 503 (e.g., with a thickness of 1 ⁇ m or less). Such a thin film would allow the surface configuration of the alignment controlling element 501 to control the alignment of the liquid crystal layer 510 .
  • FIGS. 34A to 34E are schematic cross-sectional views for explaining a method of producing the alignment controlling element 501 by using a material which is capable of thermal deformation (thermal flow).
  • a wall member forming layer (thickness: e.g., 300 nm) 522 is formed on a substrate 520 .
  • the present embodiment illustrates a case where a quartz substrate is used as the substrate 520 and a silicon nitride film is used as the wall member forming layer 522 .
  • a resist pattern 524 comprising a plurality of islet portions is formed on the wall member forming layer 522 by using a negative resist, for example.
  • the pitch of the islet portions of the resist pattern 524 along the X direction is to be selected in accordance with the pitch of the wall members to be formed, i.e., the unit feature pitch P X .
  • the average pitch of the resist pattern 524 along the X direction is 1.6 ⁇ m.
  • a resist pattern 524 comprising a plurality of islet portions is disposed, with an average interspace of 0.8 ⁇ m between the islet portions.
  • the average pitch of the resist pattern 524 along the Y direction is 3.2 ⁇ m.
  • the wall member forming layer 522 is etched by using the resist pattern 524 as a mask.
  • the wall member forming layer (silicon nitride film) 522 is subjected to a wet etching using a buffered hydrofluoric acid for 60 seconds, and thereafter is washed well with water. Through this etching, wall members 526 having a height corresponding to the thickness of the wall member forming layer 522 are formed.
  • the cross section of each wall member 526 is shown to be substantially triangular with a bottom face in contact with the substrate 520 , the cross-sectional shape of the wall members 526 is not limited to that which is shown in FIG. 34C .
  • each wall member 526 may be a trapezoid having a bottom side in contact with the substrate 520 .
  • wall member 526 each having a substantially rectangular cross section may be formed.
  • the slope member forming layers 528 may be islet portions of a resist pattern composed of a positive resist, for example. Each islet portion of the resist pattern 528 is formed so as to be in contact with one side face 526 a of the corresponding wall member 526 .
  • the resist pattern 528 is formed by using a photomask having a pattern which is shifted by 0.4 ⁇ m from the pattern of the photomask (reticle) used when forming the resist pattern 524 in FIG. 34B . Therefore, the average pitch of adjoining islet portions of the resist pattern 528 along the X direction is 1.6 ⁇ m, and the average interspace between adjoining islet portions of the resist pattern 528 is 0.8 ⁇ m.
  • the resist pattern 528 is heated to deform the resist pattern 528 , whereby the slope members 530 are formed.
  • the formation of the slope members 530 can be effected by, for example, heating the substrate 520 in a hot oven (temperature: 135°) for 10 minutes.
  • the temperature inside the oven may be any temperature which does not cause deformation of the wall members 526 and the substrate 520 but which causes thermal deformation (thermal flow) of the resist pattern 528 , and may be selected in accordance with the materials of the wall members 526 and the resist pattern 528 .
  • an alignment controlling element 600 having a plurality of unit features 532 each composed of a wall member 526 and a slope member 530 is obtained.
  • the unit features 532 have an average pitch of 1.6 ⁇ m, and the slanted face 530 a of each slope member 530 constitutes an angle of 12° with the substrate 502 .
  • Each unit feature 532 of the present embodiment has a substantially triangular cross section as shown in FIG. 4E , the triangular shape having a vertex angle (i.e., the angle between the exposed side face 526 b of each wall member and the slanted face 530 a of each slope member 530 ) of 112°.
  • slope members are formed by deforming a slope member forming layer through an oblique exposure utilizing wall members.
  • a plurality of wall members 542 are formed on a substrate 540 by emboss, for example.
  • the wall members 542 are formed by using resin black (color mosaic CK-2000; Fuji Hunt Electronics Technology K.K.).
  • a slope member forming layer 544 is formed so as to fill between adjoining wall members 542 and cover any surface portion of the substrate 540 on which the wall members 542 are not formed.
  • FIG. 35B shows the slope member forming layer 544 to have the same thickness as the height of the wall members 542 , the two values may be different.
  • the slope member forming layer 544 is a layer composed of, for example, a negative resist (OMR85; Tokyo Ohka Kogyo Co., Ltd.).
  • the slope member forming layer (nega-resist layer) 544 is subjected to an oblique exposure.
  • the direction of exposure may be selected in accordance with the direction in which the slanted faces are to be formed. As a result, only portions of the nega-resist layer 544 which are not shaded by the wall members 542 are exposed.
  • any surface region of the substrate 540 other than the regions to be exposed in this step may be covered with a mask.
  • any surface region of the substrate 540 which has been exposed in the step shown in FIG. 35C may now be covered with a mask, and any region of the nega-resist layer 544 not covered with the mask may be subjected to an exposure from a direction which is different from the direction of exposure shown in. FIG. 35C ( FIG. 35D ).
  • a plurality of instances (which may be three times or more) of oblique exposure can be performed, each time with a different direction of exposure.
  • the oblique exposure illustrated in FIGS. 35C and 35D may be performed from the back side of the substrate 540 .
  • an alignment controlling element 601 having a plurality of unit features 548 each composed of a wall member 542 and a slope member 546 is obtained. Note that, in the case where a plurality of instances of oblique exposure are performed while switching the direction of exposure as shown in FIGS. 35C and 35D , the slanted face of each unit feature 548 has a normal direction which depends on the direction of exposure to which that unit feature 548 was subjected.
  • slope members are formed by deforming a slope member forming layer.
  • slope members can be formed without performing any such deformation step.
  • slope members are formed by applying a solution to a substrate by ink jet technique, using each wall member as a dam. Therefore, there is no need to perform a step of deforming a slope member forming layer as in the methods illustrated in FIGS. 34A to 34E and FIGS. 35A to 35E .
  • a plurality of wall members 552 are formed on a substrate 550 by emboss or the like.
  • the wall members 552 may be formed of a positive resist (OFPR800, Tokyo Ohka Kogyo Co., Ltd.), for example.
  • the material of the wall members 552 may be any material having a relatively small surface tension, and does not need to be photosensitive.
  • any surface region of the substrate 550 other than the regions to be exposed in this step may be covered with a mask.
  • any surface region of the substrate 550 which has been exposed in the step shown in FIG. 36B may now be covered with a mask, and the wall members 552 which are in any region not covered with the mask may be subjected to an exposure from a direction which is different from the direction of exposure shown in FIG. 36B ( FIG. 36C ).
  • the oblique exposure illustrated in FIGS. 36B and 36C may be performed from the back side of the substrate 550 .
  • a solution for forming slope members is applied to the surface of the substrate 550 , by using e.g. ink jet technique.
  • the solution is repelled by the water-repellent side face 552 b of each wall member 552 , so as to adhere to the hydrophilic side face 552 a of each wall member 552 and the surface of the substrate 550 .
  • the applied solution is dried, whereby slope members 554 each having a slanted face 554 a are formed.
  • a hydrophilic (aqueous dispersion type) ink e.g., polyvinyl alcohol, may be used.
  • a hydrophobic (organic solvent type) ink may instead be used as the solution for forming the slope members.
  • the impartment of hydrophilicity or oleophilicity to the side faces 552 a of the wall members 552 which is done in order to enhance the wettability with respect to the solution for forming the slope members, may be expressed as impartment or enhancement, etc., of “lyophilicity”.
  • an alignment controlling element 602 having a plurality of unit features 556 each composed of a wall member 552 and a slope member 554 is obtained. Note that, in the case where a plurality of instances of oblique exposure are performed while switching the direction of exposure as shown in FIGS. 36B and 36C , the slanted face 556 a of each unit feature 556 has a normal direction which depends on the direction of exposure to which that unit feature 556 was subjected.
  • alignment controlling elements 600 , 601 , and 602 which can control the initial alignment of a liquid crystal layer with an entire surface which is in contact with the liquid crystal layer can be easily produced.
  • an alignment controlling element 600 , 601 , or 602 there is provided an advantage in that the alignment of the liquid crystal layer can be controlled more uniformly.
  • the angle between each slanted face and the substrate surface, the height of each wall member, and the like can be arbitrarily and precisely set, even if the average pitch P X of the unit features of the alignment controlling element is reduced (e.g., several ⁇ m or less). Since the angle between each slanted face and the substrate surface can be easily adjusted based on the pitch, height, and the like of the wall members, a high pretilt which was difficult to obtain with conventional methods can be realized.
  • the alignment controlling element 501 shown in FIG. 32A can alternatively be formed by emboss (replica technique).
  • emboss replica technique
  • a master having a plurality of unit features on its surface is produced by a method similar to any of the methods described with reference to FIGS. 34A to 34E , FIGS. 35A to 35E , and FIGS. 36A to 36D , for example.
  • the surface configuration of the master is embossed to a layer of resin material (resin layer) or the like, thus forming an alignment controlling element 501 .
  • the resin layer may be disposed on a glass substrate, for example.
  • an embossed master may be obtained by embossing the aforementioned master, and the embossed master may be used to form the alignment controlling element 501 by performing further emboss.
  • the liquid crystal display device of the present embodiment has a similar structure to that of the liquid crystal display device of Embodiment 7.
  • the normal direction of a slanted face 507 a of each unit feature 503 is slanted in a different direction (different azimuth) depending on the specific location on the surface of the substrate 502 .
  • the normal direction of the slanted face 507 a refers to a direction perpendicular to the line 507 A shown in FIGS. 33C and 33D .
  • the alignment controlling element of the present embodiment includes 200 ⁇ 600 unit regions (300 ⁇ m ⁇ 100 ⁇ m).
  • each unit region 574 is halved both longitudinally and laterally, thus resulting in four subregions 580 .
  • FIG. 37B is an A-A′ or B-B′ cross-sectional view of FIG. 37A .
  • each subregion 580 has a plurality of unit features 576 arranged therein.
  • slanted faces 576 a of the unit features 576 have substantially the same normal direction.
  • the slanted faces 576 a are formed so as to face outward from the center of a unit region 574 in which that subregion belongs.
  • the unit features 576 are arranged with an average pitch P X of 1.6 ⁇ m in a direction perpendicular to their own ridges. In the direction of the ridges, the unit features 576 are arranged with an average pitch P Y of 3.2 ⁇ m, with grooves of 0.8 ⁇ m being formed therebetween.
  • the normal direction of the slanted face of each unit feature is slanted in a direction which is predetermined in accordance with the specific location of the unit feature on the substrate surface. Therefore, so-called alignment division is realized, where the pretilt direction in the liquid crystal layer is controlled with respect to each predetermined region. As a result, the viewing angle characteristics of the liquid crystal display device can be improved.
  • the structure of the alignment controlling element of the present embodiment is not limited to that shown in FIGS. 37A to 37C .
  • the size of the unit regions 574 , the number and shape of subregions, etc. can be arbitrarily set.
  • each unit region 574 has a size corresponding to the size of each pixel of the display device to which the element is to be applied.
  • the size and pitch of the unit features 576 can be arbitrarily set.
  • the alignment controlling element may have an alignment film and/or a conductive film on its surface. In this case, the liquid crystal layer may advantageously be placed so as to be in contact with the alignment film.
  • wall members 526 are formed on a substrate 520 , except that a resist pattern 524 shown in FIG. 34B is to be formed in accordance with the unit feature arrangement as shown in FIG. 37A .
  • a resist pattern 528 is formed by using a photomask in such a manner that, in each subregion, the pattern is in contact with a side face 526 a of the wall member 526 on which a slanted face is to be formed.
  • a photomask is to be used such that a pattern which is shifted by 0.4 ⁇ m in the upper right, upper left, lower right, or lower left direction from the resist pattern 524 for forming the wall members 526 is formed in the upper right, upper left, lower right, or lower left subregion, respectively, of the unit region shown in FIG. 37A .
  • unit features each of whose slanted face is oriented in a different direction depending on the specific location on the substrate surface can be easily formed.
  • the alignment controlling element of the present embodiment may be produced by a method which utilizes exposure-based deformation of a slope member forming layer, similarly to the method described with reference to FIGS. 35A to 35E .
  • wall members 542 are formed on a substrate 540 in accordance with the unit feature arrangement shown in FIG. 37A .
  • steps of oblique exposure for the nega-resist layer 544 as shown in FIGS. 35C and 35D are performed as follows. First, a first oblique exposure is performed by using a mask which covers any portion of each unit region other than the upper right subregion. Similarly, second, third, and fourth oblique exposures are performed, each by using a mask which covers any portion of each unit region other than the lower right, lower left, or upper left subregions. The first to fourth oblique exposures are to be performed with respectively different directions of exposure. Thereafter, the nega-resist layer 544 is developed ( FIG. 35E ), whereby an alignment controlling element whose slanted faces are oriented in different directions from subregion to subregion is obtained.
  • the alignment controlling element of the present embodiment may also be produced by a method similar to the ink jet technique-based method described with reference to FIG. 36 .
  • wall members 552 are formed on a substrate 550 in accordance with the unit feature arrangement shown in FIG. 37A .
  • a first oblique exposure is performed by using a mask which covers any portion of each unit region other than the upper right subregion.
  • second, third, and fourth oblique exposures are performed, each by using a mask which covers any portion of each unit region other than the lower right, lower left, or upper left subregions.
  • the first to fourth oblique exposures are to be performed with respectively different directions of exposure.
  • a solution for forming slope members is applied to the substrate 550 by ink jet technique or the like, and thereafter the applied solution is dried ( FIG. 36D ), whereby an alignment controlling element whose slanted faces are oriented in different directions from subregion to subregion is obtained.
  • an alignment controlling element in which the pitch, height, slanted face angles, etc., of the unit features are arbitrarily and precisely controlled, and which permits alignment division, can be easily produced.
  • the alignment controlling element of the present embodiment may have a surface formed by emboss.
  • Such an alignment controlling element can be formed by a method similar to the emboss-based method for forming the alignment controlling element as described in Embodiment 7.
  • a master corresponding to e.g. the upper right subregion may be produced, and the surface configuration of the master may be embossed four times for different regions, each time in a different direction, whereby an alignment controlling element in which the normal direction of the slanted faces are different from subregion to subregion can be obtained.
  • ruggednesses formed on a surface which is in contact with a liquid crystal layer impart a substantially uniform pretilt to the liquid crystal molecules located at a middle level along the thickness direction of the vertical alignment type liquid crystal layer, whereby liquid crystal alignment can be controlled with a high precision. Therefore, a bright and high-contrast liquid crystal display device can be provided.
  • the pretilt angle and the pretilt direction can be freely set.
  • the alignment of the liquid crystal layer can be regulated by a two-dimensional plane, better response characteristics can be obtained than is possible with any conventional display device utilizing rib technique or incliened electric field technique in which an alignment regulating force is linearly (one-dimensionally) applied.
  • each pixel is divided into a plurality of regions of different pretilt directions. Furthermore, a region of the same pretilt direction within a single pixel can be further divided into a plurality of regions having different pretilt angles. Thus, a liquid crystal display device having excellent viewing angle characteristics can be provided.
  • the alignment controlling structure (ruggednesses) according to the present invention has an advantage in that it can be formed with a high precision through an easier process than that required for producing any conventional alignment controlling means.
  • the present invention is applicable to various types of vertical alignment type liquid crystal display devices.
  • the present invention is particularly suitable for MVA mode liquid crystal display devices.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Mathematical Physics (AREA)
  • Architecture (AREA)
  • General Physics & Mathematics (AREA)
  • Nanotechnology (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biophysics (AREA)
  • Liquid Crystal (AREA)
US11/109,936 2004-04-22 2005-04-20 Vertically-aligned liquid crystal display device having a rugged structure which is in contact with the liquid crystal layer Expired - Fee Related US7929094B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2004-126357 2004-04-22
JP2004126357 2004-04-22

Publications (2)

Publication Number Publication Date
US20050237471A1 US20050237471A1 (en) 2005-10-27
US7929094B2 true US7929094B2 (en) 2011-04-19

Family

ID=35136027

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/109,936 Expired - Fee Related US7929094B2 (en) 2004-04-22 2005-04-20 Vertically-aligned liquid crystal display device having a rugged structure which is in contact with the liquid crystal layer

Country Status (4)

Country Link
US (1) US7929094B2 (zh)
KR (1) KR100743320B1 (zh)
CN (1) CN1690783B (zh)
TW (1) TWI317838B (zh)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140176835A1 (en) * 2012-04-26 2014-06-26 Panasonic Corporation Liquid crystal optical element and image display apparatus including the same
US12001091B2 (en) 2016-11-18 2024-06-04 Magic Leap, Inc. Spatially variable liquid crystal diffraction gratings

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101184064B1 (ko) * 2005-06-23 2012-09-21 엘지디스플레이 주식회사 배향막 제조장치 및 이를 이용한 액정표시패널의 제조방법
KR100709221B1 (ko) * 2005-08-18 2007-04-18 삼성에스디아이 주식회사 가요성 표시 장치
WO2008018213A1 (fr) * 2006-08-10 2008-02-14 Sharp Kabushiki Kaisha Dispositif d'affichage à cristaux liquides
CN102004349B (zh) * 2009-08-31 2014-08-20 鸿富锦精密工业（深圳）有限公司 液晶显示装置
WO2011026315A1 (en) * 2009-09-02 2011-03-10 The Hong Kong University Of Science And Technology Method of producing spatially variable pretilt angles across a liquid crystal cell
TWI460510B (zh) * 2011-12-15 2014-11-11 Innolux Corp 顯示面板及其製作方法及影像顯示系統
CN102789082B (zh) * 2012-08-10 2015-10-21 京东方科技集团股份有限公司 液晶显示面板及液晶显示装置
TWI519869B (zh) * 2012-11-29 2016-02-01 Ｌｇ化學股份有限公司 具有週期性微圖案化結構之圖案化延遲膜
EP3264169A4 (en) * 2015-02-27 2018-11-07 Sony Corporation Optical device, display device, and electronic device
JP2016173544A (ja) * 2015-03-18 2016-09-29 Jsr株式会社 液晶表示素子及びその製造方法、並びに液晶配向剤
CN104765200B (zh) 2015-05-06 2017-12-05 京东方科技集团股份有限公司 显示面板及显示装置
CN104991348B (zh) * 2015-05-19 2017-03-29 汕头超声显示器（二厂）有限公司 一种裸眼立体显示器件
CN105911741A (zh) * 2016-06-15 2016-08-31 深圳爱易瑞科技有限公司 高显示质量的液晶显示面板制造方法、液晶盒制造方法
US11067860B2 (en) 2016-11-18 2021-07-20 Magic Leap, Inc. Liquid crystal diffractive devices with nano-scale pattern and methods of manufacturing the same
KR102098764B1 (ko) * 2017-03-07 2020-04-08 주식회사 엘지화학 정점 쌍 안정 액정 패널의 액정 배향을 위한 패턴 형성방법, 이에 따라 형성된 패턴을 포함하는 액정 배향기판 및 상기 패턴의 형성에 사용된 마스크 기판
EP3447567B1 (en) * 2017-08-24 2023-07-12 Morrow N.V. Optical device with liquid crystal alignment
NL2020215B1 (en) * 2017-12-29 2019-07-10 Zhangjiagang Kangde Xin Optronics Mat Co Ltd Process for producing a lenticular device

Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01238619A (ja) 1988-03-18 1989-09-22 Sharp Corp 液晶セルの配向処理方法
JPH03150530A (ja) 1989-11-07 1991-06-26 Fujitsu Ltd 液晶表示装置の配向膜形成方法
JPH04356019A (ja) 1990-09-21 1992-12-09 Toshiba Corp 液晶表示素子およびその製造方法
JPH07175066A (ja) 1993-12-21 1995-07-14 Alps Electric Co Ltd 液晶基板用凹凸模様形成装置
US5438421A (en) 1991-04-24 1995-08-01 Alps Electric Co., Ltd. Orientation film of liquid crystal having bilaterally asymmetric ridges separated by grooves
US5717474A (en) * 1994-09-30 1998-02-10 Honeywell Inc. Wide-viewing angle multi-domain halftone active matrix liquid crystal display having compensating retardation
US5917570A (en) * 1995-02-10 1999-06-29 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Liquid crystal device alignment
WO1999034251A1 (en) 1997-12-24 1999-07-08 The Secretary Of State For Defence Bistable nematic liquid crystal device
US6067141A (en) * 1997-12-26 2000-05-23 Sharp Kabushiki Kaisha Liquid crystal display device with reduced viewing angle dependency
JP3150530B2 (ja) 1994-04-12 2001-03-26 株式会社クボタ 生物学的窒素除去装置
WO2001040853A1 (en) 1999-11-30 2001-06-07 Qinetiq Limited Bistable nematic liquid crystal device
US20010024256A1 (en) 2000-03-27 2001-09-27 Kitson Stephen Christopher Liquid crystal alignment
US6335775B1 (en) 1995-09-29 2002-01-01 Sony Corporation Liquid crystal device having liquid crystal orientation layers including repetitive asymmetrical projects along a plurality of grooves
US6362863B1 (en) 1998-09-18 2002-03-26 Fujitsu Limited Liquid crystal display device with saw-tooth alignment control layer
US20020135725A1 (en) * 2001-03-21 2002-09-26 Shinichi Terashita Liquid crystal display device and method for producing the same
US20020159018A1 (en) * 2000-09-27 2002-10-31 Fujitsu Limited Liquid crystal display device and method for fabricating the same
US20030112394A1 (en) * 1997-02-27 2003-06-19 Fujitsu Limited Alignment treatment of liquid crystal display device
US6724452B1 (en) 1997-06-12 2004-04-20 Fujitsu Display Technologies Corporation Vertically aligned (VA) liquid crystal display device
US20040150141A1 (en) 2003-01-17 2004-08-05 Chih-Yu Chao Non-rubbing liquid crystal alignment method
US6965421B2 (en) * 2002-08-14 2005-11-15 Seiko Epson Corporation Liquid crystal device and electronic equipment therewith

Patent Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01238619A (ja) 1988-03-18 1989-09-22 Sharp Corp 液晶セルの配向処理方法
JPH03150530A (ja) 1989-11-07 1991-06-26 Fujitsu Ltd 液晶表示装置の配向膜形成方法
JPH04356019A (ja) 1990-09-21 1992-12-09 Toshiba Corp 液晶表示素子およびその製造方法
US5438421A (en) 1991-04-24 1995-08-01 Alps Electric Co., Ltd. Orientation film of liquid crystal having bilaterally asymmetric ridges separated by grooves
JPH07175066A (ja) 1993-12-21 1995-07-14 Alps Electric Co Ltd 液晶基板用凹凸模様形成装置
JP3150530B2 (ja) 1994-04-12 2001-03-26 株式会社クボタ 生物学的窒素除去装置
US5717474A (en) * 1994-09-30 1998-02-10 Honeywell Inc. Wide-viewing angle multi-domain halftone active matrix liquid crystal display having compensating retardation
US5917570A (en) * 1995-02-10 1999-06-29 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Liquid crystal device alignment
US6335775B1 (en) 1995-09-29 2002-01-01 Sony Corporation Liquid crystal device having liquid crystal orientation layers including repetitive asymmetrical projects along a plurality of grooves
US20030112394A1 (en) * 1997-02-27 2003-06-19 Fujitsu Limited Alignment treatment of liquid crystal display device
US6724452B1 (en) 1997-06-12 2004-04-20 Fujitsu Display Technologies Corporation Vertically aligned (VA) liquid crystal display device
WO1999034251A1 (en) 1997-12-24 1999-07-08 The Secretary Of State For Defence Bistable nematic liquid crystal device
US6067141A (en) * 1997-12-26 2000-05-23 Sharp Kabushiki Kaisha Liquid crystal display device with reduced viewing angle dependency
US6362863B1 (en) 1998-09-18 2002-03-26 Fujitsu Limited Liquid crystal display device with saw-tooth alignment control layer
WO2001040853A1 (en) 1999-11-30 2001-06-07 Qinetiq Limited Bistable nematic liquid crystal device
US20010024256A1 (en) 2000-03-27 2001-09-27 Kitson Stephen Christopher Liquid crystal alignment
US20020159018A1 (en) * 2000-09-27 2002-10-31 Fujitsu Limited Liquid crystal display device and method for fabricating the same
US20020135725A1 (en) * 2001-03-21 2002-09-26 Shinichi Terashita Liquid crystal display device and method for producing the same
US6965421B2 (en) * 2002-08-14 2005-11-15 Seiko Epson Corporation Liquid crystal device and electronic equipment therewith
US20040150141A1 (en) 2003-01-17 2004-08-05 Chih-Yu Chao Non-rubbing liquid crystal alignment method

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
G.P. Bryan-Brown et al., "Grating Aligned Bistable Nematic Device", SID 97 Digest, pp. 37-40, 1997.
J. Cognard, "Alignment of Nematic Liquid Crystals and Their Mixtures", Molecular Crystals and Liquid Crystals Supplements Series, Supplement 1, 1987.
J.C. Jones et al., "Meeting the Display Requirements for Portable Applications using Zenithal Bistable Devices," SID 2002 Digest, pp. 90-93.
T. Uchida et al., "Liquid Crystal Orientation on the Surface of Obliquely-Evaporated Silicon Monoxide with Homeotropic Surface Treatment", Japanese Journal Appl. Phys., vol. 19, pp. 2127-2136, 1980.
Y. Kawai et al., "Control of nematic liquid crystal alignment using an ultra-fine periodical structures", Preprints of 2002 Liquid Crystal Symposium, pp. 111-112.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140176835A1 (en) * 2012-04-26 2014-06-26 Panasonic Corporation Liquid crystal optical element and image display apparatus including the same
US9500874B2 (en) * 2012-04-26 2016-11-22 Panasonic Intellectual Property Management Co., Ltd. Liquid crystal optical element and image display apparatus including the same
US12001091B2 (en) 2016-11-18 2024-06-04 Magic Leap, Inc. Spatially variable liquid crystal diffraction gratings

Also Published As

Publication number Publication date
KR100743320B1 (ko) 2007-07-26
CN1690783A (zh) 2005-11-02
TW200602763A (en) 2006-01-16
CN1690783B (zh) 2012-07-18
TWI317838B (en) 2009-12-01
KR20060047366A (ko) 2006-05-18
US20050237471A1 (en) 2005-10-27

Similar Documents

Publication Publication Date Title
US7929094B2 (en) Vertically-aligned liquid crystal display device having a rugged structure which is in contact with the liquid crystal layer
JP5067684B2 (ja) 液晶表示装置及びその製造方法
KR100732025B1 (ko) 액정 표시 장치용 기판 및 그를 이용한 액정 표시 장치
US8269935B2 (en) Liquid crystal display
KR100329695B1 (ko) 액정장치및그정렬방법
US20090002612A1 (en) Liquid Crystal Display Panel and Fabrication Method For Liquid Crystal Display Panel
US7602461B2 (en) Diffusion reflector and manufacture of the same
KR20040050059A (ko) 액정 표시 장치
CN1145121A (zh) 双稳态向列相液晶装置
CA2212722A1 (en) Liquid crystal device alignment
US6549257B2 (en) Structure of a multi-domain wide viewing angle liquid crystal display
JP5079409B2 (ja) 液晶表示装置及びその製造方法
TWI391759B (zh) 液晶顯示器及其製造方法
JP4275097B2 (ja) 液晶表示装置およびその製造方法
JP3939341B2 (ja) 液晶デバイスの配向
WO2010100920A1 (ja) 液晶表示装置およびその製造方法
JP4076768B2 (ja) 液晶表示装置
KR100516050B1 (ko) 광시야각수직배향비틀린네마틱액정표시장치
KR101024481B1 (ko) 액정 표시 장치의 제조 방법
KR100521265B1 (ko) 광시야각 액정 표시 장치 및 그 제조 방법
KR101112558B1 (ko) 액정 표시 장치
KR100611045B1 (ko) 광시야각 액정표시장치 제조방법
KR19990026579A (ko) 유기 절연막을 이용한 다중 영역 수직 배향 비틀린 네마틱 액정표시 장치
JPH09244023A (ja) 反射型液晶表示素子
KR19990010207A (ko) 시야각이 향상된 액정 표시장치 및 이에 사용되는 액정 셀의 형성방법

Legal Events

Date Code Title Description
AS Assignment

Owner name: SHARP KABUSHIKI KAISHA, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KAWAMURA, TADASHI;REEL/FRAME:016499/0837

Effective date: 20050329

STCF Information on status: patent grant

Free format text: PATENTED CASE

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FEPP Fee payment procedure

Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 4

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 8

FEPP Fee payment procedure

Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

LAPS Lapse for failure to pay maintenance fees

Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20230419